On my '02, I have an Actron CP-9145, it's a reader/eraser, as well as a number of real-time engine/sensor monitor readouts - will visually display IAT, MAP, RPM, % load - and many other readings, 99 in all as I recall, and you can watch them as you drive, and compare against dashboard readouts for the ones also displayed there.
I think mine ran about $180 or so - and you'd want to make sure whatever you get will work on the OBD version for your specific year truck...