shykyle

I've had some problems with my Mustang for the last couple months, running fine up up to 55 mph, but anywhere between 60 - 70 mph, lots of hesitation and "clunking". seems to run fine after 70mph also. Today, the limp home light came on, and I took it to the dealer. they performed a diagnostic, and said they weren't able to retrieve a "code". this is the second time i've had it to the dealer. I've tried various things, and i'm not mechanically inclined, and just trying to get an idea on the probable cause. Oh, gas mileage is pretty bad.

JCON

could be any number of things, do you have a code reader or a local autozone? next time it flashes try to get there immediately to read the codes.

Nuke

Year? V6 or GT? Mileage? Mods? Maintenance done over the life of the car & recently? Define "clunking" (i'm guessing something going on with fuel delivery/spark causing intermittent acceleration which gets our heavy, noisey driveline slop involved but we need more... a LOT more).

From your description it could be 100 things. Help us narrow that down with more info.

shykyle

I'm sorry, I should have included more info. It's a 2006, automatic, 4L, 73,000 . Kept a pretty clean maintenance record, because I love this car. Last oil change, they DID get sloppy and put the air filter in wrong, which made the engine light come on. That was early December. Whats so maddening, when the wrench light came on, I drove straight to the dealer. I guess when I shut the engine off when I pulled into the bay, it reset the code. They said pretty much the same thing at the dealer. Without the code, it could be lots of things. Right before it "clunks" there's a slight hesitation before it lurches and clunks and continues on. AutoZone rep suggested I try Sea Foam in the gas and crank case. Did that, doesn't seem to be much improvement...but only one tank so far.

JCON

I wouldn't sea foam it just yet.