99 Gt no power above 4,000 rpm

[CMEFLY]

I finally made the jump from 5.0 mustangs to 4.6. But I am having trouble with the new ride. It has 118,000 miles and a 5 speed. It flat out falls on its face at 4,000 rpm and if i am at full throttle it wont go any higher but if i ease into the throttle it wil rev higher. No codes and it will rev normal with no load. Definitly worse up hill. I have changed the fuel fiter with a motorcraft filter. Any ideas woud be greatlly appreciated. Thanks, Mike

 

[blkhorse]

fuel pump

 

[ForPointSex]

My did the same thing when the fuel pump was bad. I replaced it with a SVT focus pump and it runs good now.

 

[ADRENLN]

yea somthin is wrong fuel wise, that is where the 4.6 makes all its power.

 

[96GTstang46]

I experienced a similar problem when i had a clogged cat. I had a high flow cat just puke out on me and it didnt seem like it ran funny UNTIL i opened it up and whenever it got close to 3-4000rpms so.. if you have checked everything else, might be something else to look at.. Just my .02

 

[TrueBlue03]

Check Mass airflow sensor
Fuel pump
Spark plugs

mine was bogging bad when i got on it above 3500 rpms.
1st thing i tried was changing fuel filter...which i see you already did.
Then I changed the spark plugs and cleaned the mass airflow sensor. That did the trick.

 

[justinschmidt1]

yea my 96 did this stock

 

[Mossberg]

yea my 96 did this stock

Stock NPI Stangs FTMFW!

 

[DBMSTNG]

in addition to what has already been said, check the fuel filter and run injector cleaning.

 

[CMEFLY]

Just wanted to give a update. I replaced the fuel pump with a focus pump and it runs great again. Thanks for the help.