1997 Buick Park Avenue

I bought a used park ave a couple weeks ago and it drove fine, no issues. The service engine soon light came on and has stayed on so I had the codes read. TPS and purge valve, I replaced both and the car will not change up gear until 3800rpm let off the gas and it changes up. Thought it was the tps so tried a different one, unhooked neg to battery almost a hr than it started with a high idle. Thought wire was loose on the plug cause clip broke replaced, reset again and back to the shifting gear thing again. It idles ok in park/neutral. Goes into gear good but has a pull when let off brake like it wants to go on its own. I have ideas but need opinion of what the problem is now.
April 9, 2013.

First make sure the throttle body butterfly is closing all the way. Some TPS have a bit of a slot on the mounting bolt holes so you can adjust their position upon install. See if it can be moved.