99MUSTANG5.3L

I have a 2004 5.3L that I put into a 2001 Mustang that I am having this issue with. Everything is from the donor truck;ecu,harness,TAC,pedal,etc. When you first tip into the throttle it stumbles pretty bad and also if you hold the rpm's constant and then add more throttle it stumbles also. I had the ecu mailorder tuned for a stock motor(which it is). I'm running a walbro 255 pump externally right at the tank to a c5 filter/regulator and used the factory evap purge line as the return to the tank. I haven't checked pressure at the rails because it revs fine after the initial stumble. Idle is fine also.

I can check live data on my Actron scan tool,but don't really know what to look for. Any help or ideas would be appreciated. Thanks,Mark

99MUSTANG5.3L

Anyone??? Forgot to mention that there are no codes.

sreve

iTrader: (3)

post a log file or data

Michael02hawk

iTrader: (26)

My guess would be the Throttle Follower settings.

99MUSTANG5.3L

I'll try to get info from my scan tool up tomorrow.