I am having a shifting problem....sometimes. It will take off fine in first gear and shift all the way through the gears fine (automatic), then out of nowhere it will go from first to third when taking off and will never go into overdrive. Then, its shifting fine again. Anyone have any ideas? Any help will be appreciated.

 

any codes ???

 

Well since its a 1992 I can't get the parts stores to hook it up, but I did take the TCU out and found 2 fried diodes and 2 leaking capacitors. Ordered one off amazon for 60 bucks and installed it. Shifts like new )