I have this 1988 Ram 50 4x4 with 65K original miles. It has the 2 liter engine. It has no giddy up. The power is missing. It will barely do 65 and does not pull up hills. There is a slight hesitation when on the gas so, I gave it a tune-up to include plugs. rotor, new distr. cap, oil change etc. Still the same perfromance. I cleaned the carb with Gunk. No improvement. I haven't changed the fuel filter yet and that is my next target. Besides that what else should I be looking at? FYI, the truck has very little highway miles. It was basically driven around town. Thanks for your help!

 

Check the timing belt and maybe check ignition timing