Wierd RPMs

[whatevergoof]

95 SC2 Manual tranny
Ok, here's my story...Sunday morning when I started my car it was chugging kind of funny. Well I let it warm up a little and it seemed fine. As I was driving the check engine light came on for like a minute or so and went back off. The way home it was fine. The next day on start up it seemed fine, but was chuggin when I would shift. I had to rev the engine higher than normal for it to like the shift change. Then on the way home that same day, when I started it, it seemed fine. But when I took off the rpms were jumpin all around. When I came to a stop light w/ the car in neutral, instead of stickin around 800 rpms, it jumped up to almost 2000 rpms and then fell to almost 400, at which point I gave it gas. I thought it would have died otherwise. Upon driving it home it seemed fine. Today it started fine, slight chugging at shift change, but the check engine light still flashed on, and again on the way home w/ the light. It only acts up when right after it's started up.
I'm so confused. I just replaced the ECTS a month or so ago, but it wasn't from Saturn. Also, I bought new spark plugs and haven't put them in yet. Could the ECTS be going bad again? Or does it have anything to do w/ the plugs?

[peppermrj]

Double check the wire connector For the ECTS> When they fail the connection gets corroded.

Did you clear the codes? What codes did you get? If you need to know how to get them try How to Display Diagnostic Trouble Codes
Diagnostic Trouble Code Chart for 1st Gen Saturns

Depending. High mileage and no maintenece could require plugs,wires, air filter, fuel filter, clean the throttle body, AIC valve and port and the EGR valve and port.