I have had the infamous stubbling/surging problem like most folks have discussed here. All the popular culprits have been coil packs, wires, plugs, tranny issues, possible PCM problems.
May not be a huge discovery here but I'd like to shed some light on this. I bought my car with 87k. It now has a little over a 100k on her. Since day one I've had the slight hessitation and stumbling under light engine loads, and most noticeable in 3rd or 4th gear with the TC locked up. It'* not horrible now, but still annoying and has progressively gotten worse since day one. Anyways, after really thinking about it all, i realized what could possibly be causing this, at only light engine loads? What only operates during part throttle/cruise? EGR. So I unplugged the EGR'* stepper motor to see if it changed anything. And yes, my problem is now gone. I have a bad or dirty EGR valve. I also have a CE light now too
. But, it appears to me, that even if the valve is dirty or working imporoperly, it might not set a code and the O2'* might not notice enough to set a code from the EGR'* faulty operation either. I think this is what happened in my case. ACtually, I have gotten a CE light once in while in the past month or so, after I had been driving with the surging going on for over a minute or so, then the light popped on. But this is only recently. I've had the hesitation and surging for a while with no CE light.
In conclusion I just thought I'd share what I found out. I was thinking possible coil packs too was my problem, but after discovering the EGR thing, I'm more certain I know the problem. Yeah, I'm polluting the environement more right now, but my car runs the best it'* ever run.
Gotta check out the valve soon and see what'* up.