1969 Plymouth Roadrunner High RPM Problem

Hey, I just bought a 69' Roadrunner. From what I can tell it runs just fine and drives great except for when I accelerate hard. I can accelerate slower and everything is fine. However, this is a Roadrunner and once and a while I want to be able to stomp on the gas and launch the thing. First gear seems to be fine, but when I accelerate into high RPM in second, third and fourth, the car's RPM stagnates and loses power for a second and then regains it for a second in intervals until I let go of the gas and accelerate at slower pace. I'm thinking this is probably a timing or tuning issue, but I'm no mechanic... Any thoughts as to what the problem is and what's the solution?

Freeit86, have you fixed it yet? Kinda sounds like a fuel system issue. Good luck.