Is this a bad TFI module....

[Capri306]

Well, if it's actually missing, then I'd say it's the module or the coil. Reason I say this is because the TFI is a big transistorized switch, and when mine went on my 4-banger, it did the same thing a little bit before it died. What usually goes first is the dwell, or how long it charges the coil between firing. Best thing to do is take it to a parts store and have them test it. Most will do it for free. Also take the coil along with you, and see if they can check for opens and shorts, at least.

If on the other hand the spark is just erratic, then like exgmguy says, probably a TPS. Again, you can test this with a DVOM. Good luck.

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Capri306, Moderator, The Mustang Works Online
1979 Mercury Capri, 5.0L -- C4 -- 2.73
1987 Mustang LX Notch <--- New Timeslips