rowdys jeeps

howdy folks! new to mustang forums. I mostly have jeeps and am on multiple jeep forums but my daughter has a mustang she just had to have. but hello yall. I have an issue with her 06 4.0. she was driving one day a few weeks ago and her car just slowed down automatically and it wouldn't let her hit the gas to go faster. I showed up and it would just go about 2 mph, idle speed. giving it gas would just make it die. towed it home. first thing on my mind was cats. I knew she needed a new cat cuz passenger side was rattling. thought maybe it might have clogged something up. $600 later new cats on both sides and new o2 sensors on up stream. no dice car still acting the same. rough idle about 500 rpm, very rough, shakes car. give it gas and dies. tried MAF sensor. no dice there either. put it on a scanner, no codes. thousands of systems to sense and scanner showing NO DATA on every one. thought maybe ECM. bought one and new keys. still, no dice. thought maybe fuel system. tried fuel filter, no dice. tried scanner again and it said throttle position maxed out. tried new tps and throttle body. still no dice. pulled spark plug to check for fuel cuz I couldn't hear fuel pump. tried fuel pump this morning. no dice still doing the same. now before someone throws this out there, everything that was changed was done according to spec. neg battery terminal disconnected, all relearning checks done properly and so forth. If I had hair it would be pulled out. out of options yall. any help. something im overlooking?

Dino Dino Bambino

My first thought was the fuel pump and since replacing it hasn't solved the problem, you might want to check the fuel pump relay and verify that there's power going to the pump.

Derf00

Intake manifold leak somewhere. Either a hose going to it is torn/collapsed/cracked or the intake itself is cracked or leaking.

bl817

take the intake off and put a mirror in front of the TB so you can see it from the drivers seat, then with key on/engine off, slowly depress the gas pedal and watch the TB butterfly to see if it moves at all. if it does, does it correspond to how far the pedal is depressed? if not the TB motor went out or your pedal assembly is dead. these usually throw the wrench icon. just throwing out ideas. good luck

cavediver

You need to put a fuel pressure gauge on it and confirm you have pressure. Just hearing the fuel pump means nothing. A bad fuel pump will not throw a code that you can read on over the counter OBDII scan tools. How long since the fuel filter was changed? Other than that go to a garage that has Ford specific scan tools and pay them to properly diagnose it. Just throwing unneeded parts on is far more expensive than a proper diagnosis.

bl817

what condition are the alt and battery, low voltage will cause lots of things to go haywire. good luck