My VW T4, which is 4 cylinder petrol engine 2000cc made in 2000, has got a very slight misfire at idle. We've changed the plugs, wires, rotor and cleaned the distributor cover which seems in a good condition and replaced the coil.
Cylinder pressure compression has done and is fine. Fuel pressure will be checked, we believe it's in spec as we accelerate, we have more power.
Recheck the plugs, which all seem fine, white, not black or wet.
When the engine starts, rpm goes up to about 1400, within a few minutes, it goes down to 750. But you can still here some sound coming out out of tailpipe, like "pong, pong".
No check engine code, no check engine on.
The vacuum is about 17, a very very slight swinging at idle, no at acceleration.