Sputtering and no power

[thisolechevy]

A couple of months ago my truck started to run rough and then would just die, I discovered that it was the cap and rotor and that they were fried. So I upgraded from points to hei style dist. with a little kit by flame thrower, it mounted under the stock rotor, but never got a new cap and rotor. Well about a month later my truck started sputtering and would top out at about 55mph, I talked to an uncle of mine and he said it was either the coil, cap or rotor so I replaced them all at one time and it ran GREAT no problems at all. Then last Tuesday it did it again for about 15miles until I got where I was going, then after I let it sit for a while it worked great??? then again Sunday it did it again going along fine then it just starts sputtering and tops out this time a 50mph and absolutly has no power at all so I replace the coil cap and rotor once more thinking it would work...but it didn't??I am flustered at this what could it be? my plugs and wire are about 6 months old and have 1,100 miles on them and have seen the engine up to 220+ degrees, they are just autozone cheapo's. Could these be the problem at hand? what is causing this?