Flat below 4 Grand????

[Fastball]

Ok, about a year ago I had an electrical problem with the bucking and heaving. Tracked it down to the DIS module. Replaced it with one from Auto Zone; F127.

Solved that problem, but ever since then, my low end snap is gone! When I hit 4 Grand with secondaries, she comes alive like she should. MPG went from 25 to low 20's. Re-set idle 3 times. Ran codes, comes up clean. Replaced plugs w/Motorcrafts, (no oil in wells), wires, (A/C Delco's from Rock Auto), new fuel filter, (Motorcraft), cleaned the MAF and switched out K&N to a Fram air filter, replaced camshaft sensor, and did all new brakes & rotors making sure nothing was hanging up. ?????

Now as of late my mileage is starting to come back up to around 24 mpg, but still my low end sucks! Got toasted bad by a GT 'Stang the other day and I used to run with them and even smoke 'em if it was an AT.

Any other suggestions or clues??

 

[mrecoolgar]

I have a similar problem on one of mine. No codes, no check engine light.
I plan to take it to Ford and have them scope it in a couple of weeks.
I let you know.

 

[Off Road SHO]

Sounds like your secondaries are open all the time. Have someone start the engine while you watch the butterfly shaft's stop arm. With the engine off, the springs hold the butterflies OPEN. When you start the engine, the vacuum from the engine pulls them closed. When it revs past 3850 rpm's, the ECM deletes the Vacuum and the springs snap the secondaries open again.

Check for reversed vacuum hose hook-up on the Intake Manifold Runner Control cannister on the back plenum. Also check for leaking or pinched vacuum lines. Good luck.

Tom