branson 3510i will not speed up. i checked the lift pump, even put in a new lift pump tho the pressure seems to be 3-4psi, should i expect more ? the tractor starts right up never fails,but will only run at a minimum speed, the throtel cable is ok i can see it opening and returning , tractor speeds up just a few rpm, since the tractor starts right up and runs every time i would think the fuel injector system is ok. not sure what the butterfly does, does it or is it suppose to open a needle valve, if so is there a plug i can take off to check for debre ? thanks craig