engine stumble

I have a 1992 Eclipse GS non-turbo. I have been having a problem with an engine stumble(slight miss) at part throttle. It doesn't miss at idle or when you push the gas down all the way, but mostly shows up in 4th or 5th gear. I replaced the plugs, but it still misses. I priced some of the sensors at Autozone, and at the prices they wanted I can't afford to experiment. The car has 175,000 miles on it but doesn't use hardly any oil and other than that slight miss it does just fine. Anybody got any ideas as to where to start. Joe :banghead: :banghead:

did you gap the plugs right? does it do it all the time or only when hot/cold

when u replaced the plugs did u replace the wires???

First thing to do is get a new set of NGK BPR6ES plugs and gap them to .028. Ignition problems will trypically pork you under boost, but a plug problem can also cause part throttle missing. If you datalog the car you can see it as downward spikes in the O2 voltage trace. IF the plugs dont fix it, post back. ;)

I did buy the NGK plugs and gapped them according to specs. I did not replace the plug wires at that time because they looked like they had been changed recently. Actually, the plugs weren't that old and looked pretty good, but a little whiter than I'm used to seeing.
The problem with the stumble is much worse when the engine is cold, but it does not go away completely when warm. I checked the gas mileage the other day and it's getting around 37 miles per gallon. I'm kind of looking now for maybe a vacuum leak or maybe an egr problem...what do you think? Joe

my car does the same thing(stumble) but only when I step on the gas it started when I changed the spark plugs I put in the BPR6ES but i gapped them to .030 is the .028 also for the 98 GST