1994 Jeep GC trans issue

My 94 Jeep GC 150k miles, 4L auto trans is having issues that seem to get worse in hotter weather or slow traffic. Fluid smells and looks good but trans does not want to shift after sitting in stop and go traffic or after driving at freeway speeds on warm days for a couple hours. When in drive and I slow down or stop then speed back up trans won't upshift, but I can shift to N then put back in D and it will shift. I know it must be heat related ? and I haven't changed fluid or filter yet. Any ideas ? Thanks

Sounds like something that leaks hydraulic pressure when the housing gets hot, like a crack or improperly tightened gasket section.

R.

probably time for a governor pressure solenoid and /or transducer.