Just bought a 2006 ford ranger and after driving a while the transmission overdrive light starts flashing and it starts "slamming" into gear. When you turn the engine off, the light turns off and it stops doing it, but will do it again next time driving. I hooked a computer up and it gave me 0 codes. Tried replacing the ECM, but when I put the new one in it won't start at all, but will start back up with the old one back in place HELP!

The new ECM needs to be programed to work with the anti-theft system.

Can it be programmed for my truck?

How do I program the new one if it was a swap from another truck?