I drive a 97 Eclipse with about 75k on it... for the past year i've noticed that the transmission hasn't been shifting too smoothly it feels like its jerking... almost like I'm driving a stick shift badly (but the car is automatic) I took it to a garage and paid over 200$ for scans and everything to see what was causing the problem and they said nothing was wrong with my car. about 2 weeks ago, the car started shifting extremely bad and the check engine light came on... and then it stopped shifting all together while i was driving so i pulled over, turned the car off, and restarted it and it was shifting again but the engine light was still on. i checked the tranny fluid and it was a little low so i put more in and got someone to turn the engine light off. it stayed off for the two weeks but today the same thing happened again. engine light on and no shifting.... i just wanted to see if anyone had some ideas on what it could be before i take it back to a garage to pay for more scans... thanks (:

btw there has also been a whining/whistling noise coming from somewhere under the hood, but I don't know if that has anything to do with this problem.

 

Sounds like your vacuum lead is off or broken. Make sure that you check the fluid while in park with the engine running. See if you can find where that sound is coming from. Check all vacuum lines especially any connected to the tranny. Without vacuum you will have shifting problems.