Shifts when warm ,huh.Sounds like a dirty valve body.I had an old ford that
needed 45 minutes of warm up before it swould shift into drive. Once it
warmed up, it worded fine. Before you junk it,try seafoam auto trans
cleaner at advance auto.This is not another seal conditioner, but a nasty
cleaner.Real nasty.If it works,change the fluid,and put in any of the seal
conditioners,afterwords.