Hesitation at 1500 rpms

druss42

My truck hesitates when in park at 1500 rpms. When I drive it hesitates when I give it gas and doesn't want to take off. Also the rpms fluctuate while driving. I put a new fuel pump, fuel filter, TPS sensor, distributor cap, wires and spark plugs along with a crank shaft sensor. We put on the computer and it says misfire on 3, then we change 3 and hooked the computer back up and it jumps all over the place. Can anybody help, please.