1994 Dodge Truck intermittent hesitation and timing

I have replaced the fuel pump, distributor cap and rotor and the crankshaft position sensor, and finally got it started. Starts fine but now below 2000 rpm, it has a minor miss, slowly accelerating up intermittently around 1800 rpm especially, it sounds just like it is out of time, pops and cracks, but if I move the accelerator on up it quits and runs fine, above 2000 rpm it runs fine, no miss. What can I check or maybe some pointers of where to go from here.