1995 Dodge Avenger Won't shift out of 1st gear.

I noticed that my car was idling funny when I came to a stop. It would almost die. I changed the plugs and wires. Then I also noticed that when the trans. Down shifted coming to a stop I felt small lurches. Then it started to not shift from 1st to 2nd until I reached 4000 rpm. Unless I took my foot off of the gas for a second. Now it won't shift out of 1st at all. I took it to a shop and they changed the oil and looked at the trans fluid and said that it had no shavings and the color was good. Fluid level of trans. Ok. Now it's doing it again and I can't check the fluids because the engine is idling now at 2000 rpm and I can't check the fluid. I was told by a friend that it could possibly be the control module in the trans. Is this true and if not what might be the problem?