What eng? No changes right before the prob started. Only pings/misses at 5K up at WOT? Put the timing back to where it was OK before & might T into the fuel line at the carb inlet and run a neoprene line to a round vac gauge (most have a psi side) taped to your windshield & take it back out & see if you have several psi @5000 rpm & I'm assuming it's acting up at WOT. If good there holler back