350 TPI, runs and drives great except going up long hills. Then it chugs and shakes, not enough to slow it down but enough so it won't accelerate any faster. I have done the tune up stuff, fuel filter, and had the trans flushed.

 

never expierienced that with an auto... it should be shifting to a lower gear
what does it do if you downshift it yourself?

 

I had a similiar problem a couple of years ago. The problem was that my ECM kept the torque converter clutch locked in and didn't release it at lower speeds. The cure for it is either rig up a switch or get the painless wiring setup. I got the painless setup and its easy to put in and you won't have this problem anymore.

 

I thought it might be the torque converter switch, when I did the trans flush they checked it and said it worked great. When I go over the grade I shift to drive and still have the problem. There were some pieces of clutch lining when they dropped the pan...I don't get why it accerlates without doing this, just up hills