i have a 1987 firebird formula 350. when im driving my rpm's drop and the engine sounds lower pitch and it just bogs out and i have to stomp on it to get my rpm's back where they should be. it does it in drive and overdrive on flat ground and up hills. i use lucus fuel system cleaner i swapped out my throttle position sensor pcv valve fuel filter and vaccum lines but its still doing it. if anyone has any clue pleas let me know.

 

mines doing same thing when i speed up. mines 86 305/carbed(iroc)