1998 Chevy Blazer Misfiring issues.

My 98 2-Door Blazer has been misfiring since I bought it. If I drive it easy, it is fine. But if I try to floor it, it usually just revs up and misfires really bad, sometimes it just free-revs usually around 3600rpms, but I'm confident it's not the transmission. If it's in neutral and I immediately step on it from idle, it misfires. But if I keep smooth steady throttle increase, it doesn't misfire at all.

I changed the plugs and wires last week. I pulled plug number 6 and the electrodes were pretty much touching, I fixed the plug gap and it didn't misfire at all on the way home, but started again the next day.

2nd gear is pretty weak it feels like to me, I feel like I have alot less power than I should on my truck. I think I might need a fuel pump, but thought about replacing the cap and rotor.

Any ideas guys?