when car is cold the transmission will not engage 4th gear until the transmission has heated up. whassup.

 

4th gear is, I believe, direct, not overdrive. That said, I think its normal. Most emission systems delay last upshift in order to get the engine up to temp. quickly to lower emissions quicker. I presume you've had the trans fluid changed as well as the filter before posting. If not, good idea simply based on car's age. All service manualsstate to verify fluid level and condition of fluid before any further diagnosis is attempted.

 

I had the transmission overhauled. It was doing it before and has continued since. It acts like it is vacum relater as i get black smoke out of the tailpipe during shifts.