as said it could be the distributer.also you need to check your timing.it sjould be 7* btdc give or take 2*.if you are at 9 then back it off to 7 or if you are at 7 back it off to 5.at 9* my truck will ping but it is fine at 7.

87 dodge power ram 50,35" tires,5 1/2" total lift,4.6 gears,lockers front and rear,Rancho RS5000's,custom front bumper,custom rock sliders,cct extended diff breathers,75 amp alt(40 amp stock),thorely header,K&N,wheeled hard...