I have a 90 IROC when first started engine cold it won't go in reverse untill it run's a couple minute's. after that it's fine till it sit's parked awhile. everything else seem's to be working fine. It goes right in foreward gear's all the time. The Tran's.Is a 700R4. Any help would be appreciated.

 

The 700 of that year uses a feed-bleed system (a controlled leak) that doesn't seal until reverse fully engages. With age and wear this starts to act up, although usually when hot. This can't be corrected in car. WHen it is O/H'ed this arrangement can be modified to correct this problem.