[SloPony]

On the average, this 2.3l mustang runs smooth as silk, however, on occaision, going up large hills, it'll start missing pretty bad. Sometimes, I can clear it up by shifting to neuteral and reving up the engine and it'll smooth out. It always smooths out on its own as I get to level ground.
I've tuned it up,(plugs,wires, distributor cap, rotor button)/with good parts. Ran injector cleaner through it.
I think it may be timing related, but I don't know enough about these engines to go tearing into it.
The computer isn't throwing any codes.
Help!

[SloPony]

Bump. I need an answer for this. Guys, I know I'm not the ONLY guy with this problem.

[Turbosnake]

I don't have that problem right now but I do have an intermitten check engine light that comes on for no apparent reason.

Have you put new spark plugs in it? Mine started running rough a while ago I put new spak plugs in it and it ran fine after that.

[SloPony]

Fresh plugs, wires, cap, rotor, hollowed out cat.
I'm starting to think it might be the fuel filter.

[krk105]

I know after a certian degree of incline some carberators (i.e. on my motorcycle) will not function correctly. Due to not being able to suck gas from the bowl. This same principle might be happening in your gas tank. I noticed you are from Kentuckey. How steep are the hills and how low do you run the gas tank?

[SGTCOFFEE]

I have this kind of problem too.
2 years ago it started doing that, loading up and back firing, missing going up hills or when you got on the gas pedal.
I changed my O2 sensor and it ran fine for 2 years.
Now it has started up again, so I replaced my O2 sensor but this time it did not fix the problem.
Could it be the EGR valve causing this?
I get codes 67, and 84 with just the ignition switch in the on position.