97 Ford F150 lack of power at hwy speeds

1997 FORD F-150

OTTLAW2

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97 Ford F150 4x4, supercab, 95K miles, 4.6L engine.
Fuel filter, spark plugs, K&N filter serviced within 15K miles.
For the last 20K miles when going down the hwy above 65MPH, when I want to accelerate the truck does good for the first 3-5 seconds and then there is a noticeable drop in power. It has also droppped some power at all speeds and the fuel economy has dropped to 11 to 13 MPG. It has also started to "ping" under light acceleration, or at least I think it is as you can hear what I think is pinging but it sounds like it is under the truck by the catalytic converters.
I have tried several gas treatments without any meassure of success. I do not notice any fuel smell from under the hood.
Thanks for your time.
Mike

Jul 7, 2007 at 9:24 AM

MARKYMARKDOWN

MEMBER
1 POST

im having the very same issue. for me its between the erg module malfunctioning and the exhaust recirculation system is causing misfires, or valve issues (springs breaking), vacuum issues, and possibly a worn down cam screwing up the valves. this post is really old and i was hoping that if you ever resolved your issue you could help me out a bit. it sounds like we got the exact same problem exept the "pinging" sound, but if it truely is comming from the rear of the vehicle near the cat. converter, thats more than likely your transfer case or limited slip (possibly possitraction, but its one or the other) and that would be a completely different problem. HELP would be very appriciated!! Thanks,
Mark Gillitzer

Dec 31, 2011 at 1:19 PM

JACOBANDNICKOLAS

CAR REPAIR CONTRIBUTOR
110,190 POSTS

Check to make sure the catalytic converter isn't plugging.

Jan 30, 2012 at 12:42 AM

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