My friend and I replaced the alternator and battery on my 97 SSE this weekend.

however, since then, the rpms have been acting wierd

at idle, the needle is around 750, but completely randomly, it just moves up a little, then back down, with no pattern.

Earlier I posted the car sometimes shudders, and RPMs go up and down on fractions of like 100s of RPMs.

but now, even when im driving, the rpms just waiver all over... it hasn't stalled out, but it idles rough. Could we have screwed something up by replacing the alternator, I can't imagine what would have been effected though....? I did wires and plugs recently too.

Check your ignition system... the wires, the plugs.. and hopefully not the coil packs

Also sounds like your engine is hunting for the idle spot. You could have a restriction in the intake tract.

Or a textbook example of a bad tps. you scan codes yet?

Sounds like a bad TPS.

hey everybody thanks for your responses

I was thinking bad TPS myself, but there are NO codes stored

I cleaned the throttle body, MAF, even had the injectors ran through the machine

still no good

now what??? I don't even have a sensor code to point me in the right direction!

With no codes, we can actually narrow it down some. It'* probably not the TPS or the MAF sensor. How old are your O2 sensors? If they're stock I'd recommend changing at least the one in the downpipe. If it'* reading wrong, it can try to run you too lean or too rich. You have the pre-heated type, they run about $60, and stay away from Bosch!

Your IAC could be a problem, or the TB itself. If you haven't done so, I'd suggest removing the TB and cleaning it thoroghly. Be very careful with the MAF sensor. You may also want to check your fuel pressure at the rail, and replace the fuel filter if it'* due.

I'm not leaning this direction, but go ahead and check out your coil packs. I posted a section in Techinfo on this topic. Pull one or two plugs and inspect them, too. You want light tan deposits, nothing else.

Just a few ideas. With no codes, it makes it a bit harder, but usually means less expensive to fix, too!

Also, I forgot to mention...

Since I've bought it, occasionally on the freeway, around 60-70mph, the car will shake, hesitate, and the RPMs will quiver, similair to what I originally posted for...

It only does it when I've drive it for a long time in a row, and when it'* slightly humid out...

???

I really would like this car to run right, I thought Bonnie'* were supposed to be very well built!

I seem to be having the exact same problem with my 94 SE. I'm going to see my GM mechanic friend this weekend and if we find problem, I will let you know. If you solve it before us, let me know!