Q: I have a 2000 Toyota Avalon when I get on the gas it won't accelerate now it starts then shuts right off

Check for diagnostic trouble codes which might provide sufficient clues. If, though, no codes have been stored, you can consider the typical causes for immediate stalling which are a faulty mass airflow sensor, faulty engine coolant temperature switch/sensor (typically at cold start only), faulty camshaft or crankshaft position sensors, worn spark plugs, wires or defective ignition coil(s), inadequate fuel delivery or pressure (clogged fuel filter, injectors, faulty fuel pump or pump circuit), contaminated or old gasoline, defective throttle position sensor, faulty idle air control valve, leaks in the EGR system, intake vacuum leaks, and so forth. If you request an engine stalling diagnostic the responding certified mechanic will get this resolved for you promptly. If you have further questions or concerns, do not hesitate to re-contact YourMechanic as we are always here to help you.