Last week did a pretty full Tune Up...seems though that since then at idle my rpm fluctuates 100-200 rpm. Kinda goes up and down. Could I not have all cylinders firin away? When I put the new rotor on, do I have to have it in the EXACT spot the other one was in???

 

Yes you do, but it should actually only fit in one way. If you got the cap on, then it's right.

 

Ok. So you think the fluctuating RPM is due to something else? It didn't seem to do it before I did the tune-up...

 

Pull the codes. Did you follow the tune-up procedure printed on your emissions sticker?

 

Maybe check the plugs for cracks in the ceramic, I cracked one once and drove it for quite a while like that, I pulled the plugs to check the gap and one of them was cracked. I don't remember an idle problem but under load you could feel it missing a little. A new plug fixed everything. Very dumb on my part. Check your cap and rotor for defects. You could have knocked a vac. line loose or off. Clean the Idle air bypass valve located on the throttle body along with the throttle body. If that doesn't work, you may also want to check the throttle body gasket and intake gasket between the upper and lower. My friends 91 had a really high idle and I read on here about the intake gasket problem, we took his off and it was missing a couple of the cross sections and part of the outer was gone. It had never been off before. Put it all back together and the idle was back to normal. You may want to change the fuel filter and run a tank of injector cleaner through the tank or take them off when you have the intake off and take them to a shop for service. I had mine done in a few hours for 108 dollars, backflushed, flow tested, new screens and tips, shops can also clean them while they are in the vehicle if you can't find a place to do it try the performance diesel shops if any in your area, I found one that had a 20K dollar injector cleaning machine that was really cool. I bought some at a junkyard for a dollar each and had them cleaned and ready when I took the intake off I took out the old ones and put in the new ones. Hope that helps.