i have a 04 ranger 4.0 i was driving down the road yesterday when i lost all power and noticed the gas was cut to the engine so i reset my inertia switch and it started right up. however i was on my way home today and about half way there i noticed the engine to not be idling as high as usual and it has a deep low sound instead of a louder more powerful sound almost like it isnt getting enough fuel or some of the cyllanders arent firing. i cant figure it out for the life of me

 

Inertia switch needs to be replace, IF it was tripped, these are for temporary use only after being tripped once.
What is the history of the vehicle?
Was it every in an accident?

And just out of curiosity how did you "notice gas was cut"?


But that has nothing to do with second issue.

Failing/low pressure from fuel pump is noticed at high demand(highway speeds) not idle.

Computer sets the idle RPMs using the IAC(idle air control) valve, there is no "idle screw", so lower idle would be IAC valve or computer issue.

4.0l SOHC engine with automatic in Park would idle at about 750rpm warmed up
Manual about 650rpm

Cold engine idle is based on engine temp, 1,100rpm would be minimum, it can be as high as 1,500rpm in freezing temps

 

its idling at about 600 and yes i hit a deer back in november but it didnt trip im thinking it finally just jared out after potholes and bumps since then. i noticed gas had stopped cause when it lost power i turned the ignition and listened for the fuel pump thats what made me think to check the switch

 

OK, then get an new inertia switch, if it tripped it is done.
For obvious reasons a "used" inertia switch would probably not be a good gamble, especially from a wrecking yard, lol, new would be best.

So I assume a manual trans?

If an auto then yes that is too low, cleaning IAC valve is the first step