Truck was running fine. Started not wanting to shift into high gear. Come up to a stop sign, check engine light comes on and it will barely move. Transmission never down shifted. Tried to pull the codes, but nothing happens when the jumper wire is plugged in. Check engine light does not flash. Figured shift solenoid was bad. Changed them and everything was good for around 50 miles. Started to exhibit the same issues of not wanting to shift into high gear. Started it one afternoon and while I was waiting for it warm up, the idle drops down fast and the check engine light comes on. Go to move it and the transmission is stuck in I’d say 3rd gear. Same situation, can’t pull the codes. Some research lead me to possibly the TPS. Changed it and nothing. I’m lost. Anyone have an idea? ECU maybe.