Haven't you guys ever heard of "corrected horsepower"??? A little something to do with barometric pressure and temperature.
I had the exact same problem with my 5.0 last fall. It ended up being the TFI module going bad. Luckily for me it was going slowly, so I could at least get to a parts store and install a new one. Check yours out and read the plugs.
...mebbe needs a T-stat & coolant change, tune up, and a timing check while you're at it???
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Capri306, Moderator, The Mustang Works Online
1979 Mercury Capri, 5.0L -- C4 -- 2.73
1987 Mustang LX Notch
[This message has been edited by Capri306 (edited 04-20-2001).]