1999 F-100 rough Idle, mid range stall and low RPM

[DesertDweller]

1999 F-100 LTRY 67F L 306064
110 Hrs only.
Initial problem was stalling in midrange 2K to 2700 rpm,when throttle was advance slowly.
I adjusted the mixture and it got a little better.
After a while the engine sputtered at idle, like backfire through the carbs?
Replaced the sparkplugs with ngk LFR6A (it was all they had in Mexico)
Seemed better.
Then it went downhill it sputtered more at idle and now I can't get my top RPM (was 5300 with this prop) now only 4900.
When in neutral , the midrange problem does not seem to occur, only under load.
Q. Is rejetting common on these engines?
Is cleaning the carbs a dealer job?

Thanks,
Peter

 

[robert graham]

Re: 1999 F-100 rough Idle, mid range stall and low RPM

carbs probably need cleaning. a dealer can do it for you for approx. $150 have carbs ever been cleaned? install fuel/water seperator. use Stabil Marine all the time. Good Luck!

 

[DesertDweller]

Re: 1999 F-100 rough Idle, mid range stall and low RPM

Supposedly they were rebuilt at some point, but I can't verify that.
It does have a water separator on it.
Thanks for the reply.
Peter