hesitating after 30 min on highway

[jmatt07]

me and a few few friends decided to take a lil trip to columbus which is a lil over an hour from where i live. well we stop at a gas station to get a drink and start back on highway. the car starts hesitating really bad, the only time it didnt hesitate was when i dropped it in 4th and kept rpms above 2500. it felt something like on a carbeurated car when it dumps too much fuel in. well it went away after about 5 min and after i dropped it into 4th gear and gunned it up to 4500rpm and then went back in 6th then it was fine. it did the same thing coming back on the trip. anyone know whats causing this? its a 98 ss with newly done h/c/i and headers swap.

[Sarge]

Sounds like a tune is needed. She appears to be starving for fuel or timing.