TBI 454... bad hesitation. Just doesn\'t \"open up\" What would cause a TBI motor to just bog down when stepping on the gas? It does it really bad when it's cold. Idles fine, but when you go to give it gas to accelerate, it just bogs down. If you really get on it, it sounds like you can hear the butterflies on the TBI unit open up, but it doesn't do anything. If you just barely step on the gas, and accelerate slowly, it seems fairly smooth. It seems to improve when the motor is totally warmed up, but it still doesn't open up like it should.