Hey, lui. I ran across your post and noticed the list of things which may cause your problem pretty much relate to later model "computer" cars. Yes It does state "disregard if these don't apply". And most don't.
Has your Mustang been recently tuned up (say within the past 5 to 6 thousand miles)? If so, did it receive a "minor" tune. Plugs, points, condenser, cap, rotor, timing checked and set, air filter and so on? Or has it had a more extensive "major tune", which would add the additional steps of carbureator work, compression check, fuel system testing, plug wires, and so forth?
I ask you this because it relates directly to a diagnosis of the problem you are having. Without knowing your Mustangs condition. I can give you some speculation of common causes and relatively simple remedies.
If indeed the pony is tuned up, start with the "most likely" causes. Fuel filter. Fuel pump. Carbureator.
An inexpensive fuel filter can cause the problem. Next a not too expensive fuel pump could be cause. Leaving the carb. (Notice how I abbreviated it this time. 'Cause my spelling is not good!) Which VERY well can be the culprit.
Your Mustang, as stated.V-8, I'm guessing a 289 with a Ford 2 bbl carb. These carbs have their pros and cons. When they are clean and set up right they are excellent. They are however prone to picking up varied stuff within the fuel bowl which quite often can cause your symptoms (and a lot worse).
It wouldn't be the first time the top was pulled on one of these 2 barrels, float lifted out, revealing some sort of crap settled over one or both the main jets.
Your starting and idle could still remain intact, but any sort of rpm or power developement would react as you have described. Additionally, heavy or full throttle, (in some cases) may still be functional. I, m NOT saying to go out and nail the throttle around the block a few laps.I'm just saying!
SO. If this gives you some direction. Get back to me if you are still at a loss to curing the pony. With some more detail, maybe I could be of more help.
Neverenough
Sunday, April 18th, 2010 AT 11:43 PM