88 740 floods, help!

[Brownji]

Installed used low mile engine in a 1988 740 GLE non turbo cranks good cold and runs good but when cut off and restarted engine acts as if it's flooded(rich). I have good fuel pressure and good spark and have changed pump relay,coolant sensor. The old engine did not have this problem also I have swapped all old parts off old to new engine,the only electronic part I have not changed is the computer any suggestions?