1995 Dodge Ram 1500

I have received a 1995 dodge ram 1500 that apperently has been worked on by some one other than me. I dont know what was done before I received the truck.I have two codes one for the transmission temperature sensor to high, and one for ECT sensor voltage too high. I also have a rough idle, eventually stalls, backfires through throttle body when throttled up. Replaced all spark plugs, all spark plug wires, cap and rotor, ignition coil, IAC motor, distributor pick up coil assembly (camshaft sensor), ECT sensor, installed new seal kit on injectors (new o-rings when I got the truck the fuel injectors were not all the way down in there holes), checked fuel injectors with an ohm meter they read roughly 12.4. Cleaned injectors, have 42 psi fuel pressure to fuel injection rail, checked for vacuum leaks, did not find any. Checked all grounds. They were all in the right spot and tight. This truck is missing its catalytic converter. Any help or information on my problem would help me greatly. Thank you