In my Toyota Vitz 2007 (automatic transmission), I have facing a problem for about a week now. The problem is, sometimes when I press the accelerator, engine revs up but car does not accelerate much.

If I release the accelerator and pressed again, the vehicle catches up and accelerates. The problem is more apparent when I am going up a hill.

Also, there had been another problem for some time now, that is, when I accelerate from a complete stop, car sometimes accelerates with 2 or 3 quick jerks.

I have changed transmission fluid about 20,000 km (about 2 years) ago.

Is it possible to check transmission fluid level in my car? I can't see any dipstick similar to the one for checking engine oil level.

Also my engine wiring harness has some problems and I have soldered several broken wires. Mostly due to this, the car idles roughly. I am looking for a new aftermarket wiring harness these days.

Could the wiring harness problem have a relation to the acceleration problem?