How long was the '85 sitting before receiving the new engine? My '85 SE backfires and stumbles, etc. I'm sure this is mostly due to the gas which averages two years old. The engine ran fine before.
There are a lot of threads about the wild tach that has also appeared after the hibernation. Some of the people who suffered from the tach problem described my other symptoms perfectly and stated the car had been sitting a long time.
Other than some Seafoam and a new ICM (which had failed) it has gradually gotten better on its own as nw gas is added. I anticipate this taking quite a while. I'm not about to drop the tank, so I can only dilute the bad stuff a little at a time. It's so unpleasant to drive it will take quite a while to use a few tankfuls.
[This message has been edited by 85 SE VIN 9 (edited 08-19-2014).]