Anybody got any ideas. The car has a stumble or hesitation at low to mid throttle but it goes away if I go WOT. Also it only does it when the outside temp. is cold. During the afternoon when it's warm out the car runs great, but at night when the temp. drops it starts to run like crap, idles rough and has the weird stumble and miss. Opti, plugs, coil, wires, are all brand new. Any other ideas?

Thanks!

 

Did you check and clean (and I have a seating method that works well) the IAC? Clean the TB as well. If that doesn't clear it up, clean or replace the EGR and be sure it's sealing well too.

 

Stumble at part throttle, disappearing at WOT......

O2's maybe??

 

Did some more playing around today and I dont think it is a secondary ignition miss. The car goes lean when it does it, but I think that's because I'm down a cylinder. I'm think I may have a fuel injector that is messed up. Since it only seems to do it lower rpm and low throttle I'm thinking maybe a injector has a funny spray pattern or is clogged. Because at higher rpm, WOT, the pulse width would be opening up allowing the correct amount of fuel. The car runs great at WOT, but it is crappy at idle, low rpm, etc. Anybody agree with my thoughts on this? I have 2 bottles of injector cleaner in the tank right now so I'll see if it gets better over the next couple of drive cycles.