Would having too much transmission fluid cause my transmission not to shift properly? Sometimes it won't change gears and when it does its a hard shift. The check engine light will come on periodically then go off. Any idea what's going on?

 

Yes, overfilled transmissions will cause problems.

As for the CEL you need to pull your codes, use this link, follow the directions and be sure to warm the truck up before doing the tests, if certain sensors aren't warmed up it will throw codes that indicating it needs warmed up and may not throw codes you actually need to see. And read the KOER test directions a couple of times and right down a small cheat sheet telling you what and when to brake, OD switch, gas WOT, etc...

 

Yeah I will probably pull the codes just to see. I'm also thinking the cat could be the problem too. The truck is 20 years old and there ain't no tellin what kind of crud is in that thing. I'm probably going to get my exhaust completely redone. Thanks for your help man. I'll be posting back soon and let you know what it was if I get it fixed.

 

Also what would be the best way to drain some of the transmission fluid?

 

Pump out through the transmission fill tube.

 

That works good, but if you don't have a pump you can disconnect one of the lines at the rad or, preferably, if you have a trans cooler w/ rubber lines and clamps, that would work.