Truck is slow to accelerate when pulling out.

It sound like your transmission is on a limp mode and you only have 3rd and second. The default will be at 3rd, but to can place the gear shifter to 2nd to get started. Note; that your going to be putting extra stress on the converter so don't push it to hard or your going to burn that out which will be a more costly repair. Common cause to this problem is a faulty wire harness or a bad shift solenoid which is an average cost of $20.00, so take is easy till you can limp it to a Transmission shop. $150.00 repair is much better then a $1,900 repair. Good luck and keep me posted, be glad to help you get your truck running 100% again soon. Almost for got, try resetting the ECM by turning the ignition to the on position (Engine not running) and pull the ECM fuse out for 30 seconds and placing it back in, start the engine. The engine may stall but let it, it's just relearning the sensor and then go for a test drive after 1 min if idling. This may get your transmission reset if there is not electrical or mechanical problems.