2001 Ford F-150 used to stall when I put it in any gear and gave it gas, so starting small I replaced the fuel filter, no biggie. Now truck stalls when I put it in reverse. Ive heard of the inertia switch but never dealt with it could this be causing my problem or do I just need to pour in some fuel additive and hope and pray?
Not the inertia switch, they have to be manually reset, like a circuit breaker in your house.
Tell us more:
Engine
Mileage
Transmission
Drive System
Last time plugs were changed
Once rolling, how does it run.
If you have not changed the plugs, have a compression check, both dry and wet, performed when you do.
Is check engine light on? If so, what codes are you getting.
Expensive way to repair: Throw parts at it and hope to get lucky.
Cost effective way: Proper diagnosis.
Sure you can through some fuel system cleaner in it, you might get lucky.
If no check engine light…I’d guess it is the idle air control valve…but that might change if I knew what engine you had.