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?

 

Sounds like it is probably the throttle position sensor - that will cause what you are getting. Did you pull and clean the throttle body? Check the wiring to the throttle body also.

May need to replace the TPS

 

I would have guessed TPS also, but if the new one didn't help ???

What's odd is that no codes are thrown. You'd think the computer would have caught something.

The only other advice I have is to start a new thread in the Tech section for your year Mustang. There's always alot more members in that section. Good luck

 

Didn't see that tps reference in the wall of text the first time through.

Still sounds like a TPS issue, check your connections. As I recall from doing Xcharger installs, there are two plugs that look similar and can be crossed.

 

I've changed the tps and the connections aren't crossed. the plugs are different and can't be plugged in cross ways. also replaced throttle body. even did the relearn procedure and nothing.

 

Is it a stock throttle body?