I have recently acquired a PS2 engine that runs fine on flat track with 10 cars behind it. When going up a 3% grade it slows from 50 smph to a craw until it reaches flat ground then it picks up speed when its back on level track. I then removed all the cars and got the same result. All my other PS2 engines do not have this problem. There is no wheel spin it just slows down to a craw.
Where should I start looking
Thanks Henry