So i got the valve covers on and my 1988 Supra N/A 5-speed manual, back together after changing the spark plugs, oil, timing belt, accessory belts and coolant. Got the car to actually start but when i hit the accelerator, the responds is slow and it wont rev pass 2000 rpm. It backfires as the rpm's go back down from 2000. Anyone else experience issues like mine?