i have a 1986 trans am with a 305 4bbl LG4. I can floor it in 1st, 2nd, and 3rd gear and it picks up speed pretty damn fast, but if i floor it in 4th or 5th it will jerk you back and fourth in your seat, bogging. And if i'm just cruising at about 40mph, i can floor it and it will actually slow me down! but if i keep it a little bit from floored, it speeds up. I dont know whats wrong, but i can get up to about 35-45 mph really easy, but after that my acceleration sucks! can anyone help me to determine whats wrong? I replaced the fuel filter and i think it might of made it a little better. but not good enough! its pretty much stock with 93,000 miles on rebuild. VERY VERY clean under the hood. K&N air filter and accel supercoil, high flow cat and Flowmaster muffler. Everything else is stock.. Thanks in advance!