Where is the oil coming from on the TB? Was your aircleaner oil free when you changed it? Is it now?
Take that junkyard tps back to the junkyard and get a new one. I had a similar problem with my '88 where I couldn't climb up hill swell and the tranny wouldn't downshift unless I floored it. Tested the TPS with a meter and it checked good. However, the symptoms pointed to the TPS so I replaced it anyway. Problem solved.
You must also make sure you adjust the TPS correctly.
http://www1.autozone.com/servlet/UiB...3d80152308.jsp