1993 Ford F-150 Truck shacks from 25-35 mph

My question is what could be wrong with my truck. It's a 93 f150 flareside with a 5.0L 302 engine and after I changed the plug wires and distriputor cap and rotor it doesn't run right it shacks when backing up and when driving it it get to about 25 and starts shacking really bad and it does stop till you get past 35 then it evens out again. Then when you let off the gas and hit the gas again it shacks really bad it finally likes dumps a lot of gas into the engine a then it stops shacking. So what do you think a couple of Buddys say they think it's the timeing and that it's off. Because the plug wires are in the right fireing order. That's been checked more than once andthey are all on the spark plugs. Your answer on how to fix this will be really helpfull.
Thanks,
Andrew