Misfire at 3700 rpm

[OrangeFiero]

Ok, so ive got this strange misfire going on at around 3700 rpm in every gear but 1 and 2. I bought the 325 about 3 months ago, and it ran fine when i bought it. The misfire is slowly getting worse but its not bad enough where a little lightness on the throttle wont get rid of it, but it does still happen at half throttle. I just did plugs because i had a broken one in cyl 1, so i replaced all of them and it ran amazing. I got headers with a used O2 sensor and the check engine light comes on every so often for it. Could just a simple bad O2 sensor create this somewhat violent and continuing misfire in high rpms? Or is that just adding to a bad fule pump, or dirty injectors or something else?

By the way i drove it with the 02 unplugged and it did it worse and in 2nd this time but same in other gears.

Any ideas?

[jlevie]

The first thing that comes to mind, given the symptoms, would be intake leaks. Have a shop run a smoke test. Also toss the O2 sensor and replace it with a brand new part.

[OrangeFiero]

Ok i just ordered plug wires, and i got a new O2 sensor, and if neither of those fix the problem, ill resort to a starter fluid test, or a smoke test depending.

[ak-]

Cap and rotor was my issue with the misfire at that rpm.
Adjusting the tps smoothed out my idle because it wasn't clicking when you slightly pulled on the butterfly/throttle.

Check for leaks as mentioned above first.

[OrangeFiero]

O2 sensor wasnt the problem... ill keep you posted when i get wires