Mitsubishi Forum - Mitsubishi Enthusiast Forums - 1996 GS Eclipse transmission problems

Hi everyone. We recently bought a 1996 GS Eclipse with the 2.0 and automatic transmission for our daughter a couple weeks ago. We didn't even get the car 10 miles to our house and the transmission down shifted hard to fourth and then would not shift back out of first. After some research, we put new input and output speed sensors on it, with no change. Took the car to have the transmission codes read and it said 4th gear ratio error. Weird thing is after resetting the codes it will shift fine for a while and then it is like it continually shifts from 4th into OD and back to 4th again. Then it will go back into "limp in" mode. If we pull over and shut the car off and restart it again it will shift fine for a while. What would be the next step in trying to figure out the problem? Any help is greatly appreciated. Also previous owner put header on and msd coil and cold air intake on it. Thank you for any help.