FUEL PUMPS

well, i put my uncles 800 holley DP on and me and my dad went for a ride!!!...went down 84east and the car WOULDNT go over 6200!!!!
1st!!!,2nd!!!,3rd!!!
my dad says its NOT fuel but it may be my dist....when i put on my PROFORM my 340 wouldnt idle or even start...i welded the weights in the dist. and it "fixed" the problem BUT now it wont go over 6200 AT ALL!!!
WOULD my dist. do this??
anybody got any good used dist. laying around??