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Completely flabbergasted-- 1999 Avalon bucking like a standard

Hi. I would first like to say thank you ahead of time for your tips. I have no idea what my problem is and i’m running out of money!

The issue: My Toyota Avalon, when floored, will hesitate to the point of going no where, once I let off the gas pedal it will go. Also, if floored, sometimes it will rev, up and down, up and down. The mystery is that this does not happen at all after I top off my gas tank. A couple days later it will begin to show up.

What I’ve replaced so far: Fuel filter, mass air flow, I swapped the throttle position sensor, but no change so I put the old one back on.

*check engine light has not come on. It was however, still throwing two codes: P0100(MAF) and P0110(intake air temp sensor) I have not yet replace the intake air temp sensor.

The transmission was checked out by a shop and they said its probably a fuel delivery system issue. They had replaced the oil and filter on it.

Does anyone have any ideas or suggestions? Could it be a fuel pump maybe? I’m tired of putting money into the car!


Poor college student.

Yes it possibly could be a fuel pump, but before you throw yet another part at it, have the fuel pressure tested.

Also check the throttle linkage and cables. You should not have to “floor” it. You probably have a stretched cable or cracked cable housing that is preventing you from controlling the throttle properly. I have a Camry with a similar engine and transmission and there is never a need to “floor” it.

When was the last time you changed the spark plugs, and wires (if it has them)?
Sounds like spark is being lost to 1 cylinder under full throttle.

If they are coil on stick instead of wires, one of the coils might be failing.