Engine misfire - jerks in 2nd gear acceleration - power kicks in stepwise

Hi everyone,

I have been driving my Suzuki Jimny 1999 (G13BB engine) for three years now, mostly without problems.
However, recently it started misfiring regularly, both in idle and when driving at low rpm.

First thing I checked was the sparkplugs and Ignition coils and surely, there was quite a bit of oil in the spark plug well at the back of the engine (4th ignition coil stick). Also the ignition stick had burn marks on it and smelled like melted rubber.

So, I replaced the gaskets on the rocker cover & replaced the 4th spark plug & replaced the 4th ignition coil stick.

Engine is now running smoothly in idle and when driving at higher rpm.

HOWEVER

Specifically when I drive away from a stop and switch from 1st to 2nd gear with low rpm/ limited speed, the engine shudders and only delivers half power. When I press on and keep accelerating (slowly) and reach higher rpm, the power kicks in. This happens consistently in two steps. So right after shifting gears there is little power, then when I reach 2000+ rpm, the engine suddenly gives more power and right after that a second powerkick which brings the car back to full power.

From what I have read on the forum there can be a variety of problems related to misfires. I am not sure if this is still a matter of misfiring or something else.

Some additional information:
- I had a significant coolant leak for a while
- changed the waterpump and timing belts 1 year ago -> fixed the coolant leak
- There is an oil + small coolant leak at the back of the engine, probably gasket near the cam sensor
- The timing belt was squeeling a little bit until I replaced the coil pack yesterday
- There is some oil on the oxygen sensor, which dripped down from the oil leak at the back of the engine. I regularly clean this
- I have had some weird electrical problem where the sigarette socket wouldn't give power to my adapter, but if I hit the side of the dashboard with my hand, it turns back on for a few seconds and then stops again. Probably a loose wire or something?

What would be the best approach in terms of one by one checking the possible causes (and which causes)?

Hope to hear from you all,
Hilmar

Try to decreese the gap on the sparkplugs?

While the 'plugs are out, do a compression test.