95 EX-R sedan
150,000 km ( less than 100k miles)
F22B1 (VTEC) with no modifications
5-speed transmission

What I mean by stumbling: The car acts like I'm trying to accelerate from a near stop while in 5th gear. I give it plenty of gas but it just has no umph... it will accelerate very very slowly.


Periodically my engine stumbles at low rpm when attempting to accelerate. then, it always kicks back in once it hits 4000rpm. (sometimes I have to depreess the clutch halfway to cause slippage and allow the engine to rev to 4000+ rpm). Above 4000 it will accelerate normally but if I drop the rpm's back down it stumbles again. This only occurs when the car is in gear and trying to accelerate. If I put the car in neutral the engine revs freely, but putting it back in gear causes it to stumble once again. Changing gears does not fix the problem unless downshifting allows me to bring the rpms up. This will happen sporatically for no appearant reason. However, it seems to occur more frequently if I downshift alot in a short span of time.When it does happen, it will do it for a few minutes and then quit it. So very odd.

Potential problem areas ruled out:

spark plugs
fuel filter
air filter
EGR ports
PCV valve

any thoughts?