Transmission Problems

[Railroadman]

My problem started when the transmission went to shift into 3rd gear the engine sounded like it was free wheeling. I let off and it caught overdrive and went on. Now the Check Engine Light is on and the Transmission starts off in 2nd gear and will not shift out. Reverse works fine. I had a mechanic check the code and he said that a shift solenoid was bad. He replaced 2 solenoids and reset the light. I made it one block the engine light came back on and am stuck in 2nd gear again. So is my problem internal and the transmission will have to be overhauled?

Thanks Railroadman