Hi i have a 2003 ford mustang gt 5spd and it recently started doing this problem as soon as it gets to normal tempature the car loses alot of power when i hit 3500-4k rpm, I put in other gears and is very strong and torqui untill it hits 4k rpm and no check engine light comes up!!! People tell me its a dirty maf sensor so i cleaned it already and same problem theres another sensor that goes to the intake pipe i unplugged it and the car shut off i started the car and when it was about to shut off i gased it and it reved pass the 4k rpm with full power "LIKE FRESLY OUT THE OVEN" any help or suggestions would be very appreciated thanks









[

 

Try cleaning the throttle body.

 

Yeah I was thinking that. Or maybe an O2 sensor starting to fail?

 

with the problem you're having i would start out (carefully) with a can of carb cleaner and see if you can detect a vacuum leak at one of the hoses. if there a no vacuum leaks at idle i would bring the engine speed close to where the problem happens and retest it.

I chased down a similar problem -- except that it was a 5.0 with a MAP sensor. the problem wouldn't occur unless the car was 1) at operating temp. 2) RPMs had to be around 3500 and throttle position was at least 50% of travel.

I went through the TPS switch, EGR valve and solenoid and 2 MAP sensors. The problem was the hose that ran under the upper manifold assembly, it fed the MAP sensor and also drew the blow by from the PCV at the rear of the intake. The hot oil from the blow by caused the hose to become spongy and when the car ran enough vacuum it would collapse the hose and kill the signal to the MAP. the hose didnt have hole in it so there was no air leak.

so if you have cleaned the MAF (with electrical circuit cleaner only), and you took a hose off and it ran better. I would do a fully check of the vacuum feeds from the engine and see what you can find.
btw: grab a shop manual and trace down some of those vacuum line to their sources.

 

Needs 16 more valves

 

 

I agree. I would say its probably a vacuum leak somewhere.

 

On a completely unrelated note

Nice car

 

No worries brotha thanks alot

 

MY STANG IS STILL THE SAME :/ HELPHAS ANY ONE EXPERIENCE THIS WITH THERE PONIES? PLEASE HELP

 

What have you tried so far? Best guess is vacuum line.

 

i changed the maf sensor and cleaned out the iac valve fuel filter and cleaned out the pvc valve and nothing an i dnt see or hear any leak im STRESSING IT ALOT!!!!

 

Did you ever fix the problem

 

Gonna try and revive this nearly decade old thread.
Curious if OP ever fixed, if anyone else is familiar with the issue or has any other suggestions.
My 02 does the exact same thing.
Runs nice and smooth when cold, gets to operating temp and then won't rev over 3500 in any gear or neutral.
I've recently changed fuel pump, filter, plugs, EGR valve. Going to try fuel injectors next but am at a loss.

 

From what I now understand about my 2002 5-spd GT, with a CEL issue - The original poster said it worked fine once he removed a 2nd sensor that was plugged into the intake tube. The 2nd sensor on an 03 is the temperature sensor, on my 02 the temp sensor is built into the MAF sensor. Clearly the temp sensor was causing the problem, should have been easy to fix.