96 Achieva shifts roughs and..

My car is totally freaking me out. First off it is a 96' Oldsmobile Achieva, 6 cyl, fuel injected, and automatic with about 115000 miles on it.
A few days ago when I would start the car, it would rev really high in park (round 2200 rpms). Also I noticed the idle speed was faster and when I was driving it, I'd let off the accelerator and it would not slow down..as if in cruise control. On top of that it would not switch gears until it reved past 4000rpms...however if I let off the accelerator at around 3000rpms, it would shift with a rough jerk.
Well on the way home last night it would die almost every time I would try to accelerate from a stopped position.

This morning I changed the air filter because it was dirty, added some fuel injection fluid, and checked the fuel filter for clogs (none).
After doing all that, it seems to have lost idle power now and it is very sluggish when driving. It still dies when trying to accelerate from a stopped position half the time. It also still has the high gear switching problem as well.

Any suggestions would be greatly appreciated. Thank you very much!