Poor acceleration, mileage, etc

[phisherman162]

91 Explorer
4.0
Automatic
139,000
So here is the deal...
I have poor mileage, the vehicle dies at a stoplight at least once a day, bad acceleration (hesitating, cutting out, etc), and, as of today, it backfires when I try to head uphill. It seems to run much better at higher speeds. I have recently replaced air filter, fuel filter, fuel pressure regulator, oil change, alternator, rear brake lines, front rotor assembly, wheel bearings, radiator, thermostat, all hoses, all gaskets on engine, and AC compressor and lines. I am checking the plugs tomorrow, and will post pics. When I plugged it in, I got codes of idle too high or out of range, and code 77 throttle not fully open.

It feels like fuel or air, maybe mixture?

This rig is my primary mover and I need to get it running. Any help would be greatly appreciated.

 

[BrooklynBay]

Welcome to this forum! It could be a few things like the IAC solenoid, MAF sensor, DPFE sensor, TPS, etc.

 

[Masterd]

Sounds like a fuel pump to me.

 

[djsk8r33]

Stalling Out? Check Tranny Fluid First!!!!!!!!

 

[aldive]

Stalling Out? Check Tranny Fluid First!!!!!!!!

Why? Please explain that statement.

 

[phisherman162]

Update

So... Plugs looked fine, MAF looks fine, although one of the two elements was a little bent. Tranny fluid levels are fine, filter changed about one year ago.

 

[boggs1227]

when i got my x i was trying to get it going and i ended up doing alot as far as like injectors,maf,dpfe / also new egr valve, but was thinking why so many things went out almost at once ( in my mind at least) and i got to looking at the upper intake manifold ...it was horrible ...apon takeing it off i turned it over after getting it out of the engine compartment a giagantic chunk of carbon fell out ! must have been half the size of a golf ball ,but i soaked the intake in 5 gallons of gas and it was spotless when done .maybe the intake system has got years of crud in it and just needs to soaked in gas to totally disolve all carbon buildup ?!

 

[///Manuel]

O2 sensor. You can also try unplugging your MAF to see how it runs.