Help needed - 2011 Jimny violent knocking, shaking, engine cuts out and fuel

Hello all! I bought my beloved 2011 Jimny back in summer 2021. And it has been perfectly fine until end of last year and since, it keeps breaking down and then coming back to life by the time rescue comes. But the same issue keeps happening. Vary mechanics have looked it over for hours and nothing is visibly wrong, and of course it runs perfectly fine for them. No warning lights have come on at any point. So, what actually happens: I have been driving along on the straight and flat, in 2WD. The speed I’ve been driving when this happens has varied from 20-50mph. When driving up to 50 on the flat and straight, the Jimny suddenly pulls back and I can’t get above 40 and get slower and slower, while
at the same time the whole vehicle shakes violently and makes a loud knocking noise until the engine cuts out and then the inside of the vehicle fills with an over powering smell of fuel. The same thing and sequence of symptoms happen every time. I get rescued and it starts fine and runs fine after! But I only get a few days out of it and it happens again and again. It spent a whole week in the garage for them to
look over and take it on runs and nothing came up. They’ve no clue what is wrong as they say there is nothing wrong. But clearly there is. 

I’ve read the thread on the death wobble, I’m not sure it’s that as the engine cuts out, I don’t control the slowing down of the vehicle, it slows down, despite my foot on the floor until the engine just cuts out after the violent knocking and shaking, and then the fuel fumes almost knocking me out. 

does anyone have any idea what it could be for me to take back to garage (if I make it!) and ask them to check? 

all help will be gratefully appreciated!

thank you
Kelly 

It sounds as if you have a misfire on more than one cylinder.  Does it do it only when warmed up?  There are a couple of sensors which are known to give trouble, or it could be one of the two coil packs gone bad.

Firstly where are you located 
Could be crank sensor
But not sure about fuel smell 

Thank you for the quick reply! Misfiring was ruled out, coils were checked and said to be in good condition. It seems to be a total mystery.

Thank you for replying so quickly! I am located in Angus, Scotland. Crank sensor hasn’t been mentioned so far, so will note that down and ask the garage to check. However when they hooked it up to diagnostics (as with each time I broke down) nothing comes up on the computer.

The crank sensor is the usual culprit for stopping when hot.
The signal disappears and the ECU thinks the engine has stopped, so no error codes are set.
Usually pouring cold water over the sensor will get it to start again, or wait until it cools down.

However, it shouldn't smell of fuel or make a knocking noise, as it stops injecting fuel and the sparks- but there could be a fuel leak as well as this fault, and the knocking could be because an engine or gearbox mount is gone.

When the crank sensor stops working the rev counter drops to zero, signifying that it thinks the engine isn't turning at all.

Thank you, that was the first mechanics first thought but fuel leak was ruled out there were no signs , as well as a choked catalytic converter, fuel filter. It happens when the engine is mid temp so not hot and not cold. It’s so strange. The first mechanic that came to rescue me spent 2 hours investigating all the possible problems that would come about from the symptoms and he said it was like they were all separate problems (which he checked) but it surely wouldn’t be possible for them all to happen at the exact same moment.

when you say mid temp.....do you mean the needle is at midway on gauge 
This is ideal temp for crank sensor to play up
I would look at getting a good second hand one to try
If you buy a new one don't buy a cheap one 

Yes, sorry I meant the needle is in the middle. Ok, I’ll look into a good second hand sensor and hope that will be it. Thank you so much.

it's located behind the alternator 
for now you could try spraying it with cold water like facade says

Are you 100% sure its not coils or plug wires? Make sure they are good ones if they have been replaced (you'll see why shortly).
I chased a misfire problem a couple years ago for weeks. Replaced coils, plugs, plug wires, still misfired badly under load. Started replacing sensors: cam, crank etc. with no luck. I took it to a mechanic around the corner from work and he could find nothing wrong either, even with his fancy scanner thingamy. checked over the fuel system, injectors etc all kinds of stuff. Eventually I gave up and took it into a reputable (but expensive) auto electrician/mechanic who specialises in diesel injection systems, asking him to check the fuel system for me properly. A few hours later he rang back and told me the brand new coils I put in a few weeks earlier were junk. They were a decent mid range aftermarket brand, (at least i thought so at the time) - VDO I believe the brand was. 
The mechanic even rang the parts store I got them from (Repco, a common chain store in NZ, a division of NAPA) and told them to give me my money back. 
​​​​​They swapped in a set of genuine coils and fixed the issue immediately.
It was misfiring and jerking and popping when you'd accelerate under load, along with a rich fuel smell as unburned fuel exited the tailpipe.
May not be your issue, but in hindsight would cost me half as much to just get genuine parts the first time round.
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Hi Hughes, the first mechanic took the plugs out and checked them all and considered they were in good condition as well as the coils. After checking there was no fuel leak, he checked for misfiring but to no avail. However, what I’ll do is when it goes back in the garage I’ll mention both suggestions I’ve got from here so far just to be extra sure!

Interestingly, I took it on a long trip at the weekend, and instead of using the E10 fuel, I used Vpower and added a shot of redex. It has been running really well. I wonder if I have two different issues that just happen to fail at the same time? Fuel management issues and the sensor?