trans. + handle

Hello, I'm a new guy to this forum. Been checking it out. Looks like a good one! Anyway, my 97 Trans Sport transmission has been acting strange. I bought it a month ago from a friend. He says the engine & trans. have been replaced or reconditioned. All fine then one day, trans stayed in 1st too long before shifting to 2nd. Near 4000 RPM. Day or so later...shifting fine...then acting up...then ok. Then on a 105 degree day, the trans. just acted like it went into neutral. Had to put lever into 1st and baby it home. Next day, it would shift, but was slipping and running up RPM. Trans. fluid was low and smelled kind of burnt, but not super burnt. I changed fluid and filter + put in a new modulator (since it was cheap) and it now shifts OK again...almost. It still wants to shift into 2nd at too high an RPM. If I let it go to 25mph or so and wait 2 or 3 seconds it will then shift and will shift just great in all the other gears. There is no more slippage now though. Van runs great except for this annoyance. Trouble coming...or matbe an easy fix or OK to run it this way?
Also, where can I get an outside door handle for my Trans Sport? Any help or advice would be great!! Sorry this question is soooooooo long, but I wanted to be specific with symptoms. Thank you!!
Lt. Clang.

You will almost need a scantool to see when the PCM calls for the shift... Also this will show slip codes if there are any stored..

It sounds like a bad solenoid, or possibly a problem with line pressure, or even a bad lip seal on an apply piston...

Hard to say for sure.. If the trans was rebuilt or freshened it may not have been done right... Also just for note, the 4T60E transmissions can and do get very hot which is not a good thing when its moving a van..

The 60E in my 95 Transport Burned up too...