2001 F150 5.4 4wd. Just last week I’ve noticed if I’m cruising 55-60 mph and I let off the throttle, it feels like you tapped the breaks. When it does this the rpm’s dip down and back up. It started out more intermittent but becoming more frequent. Trans fluid is clean and full. Can a failing IAC cause these symptoms? It starts and idles good
Any thoughts or suggestions would be appreciated.

 

Sounds like a fuel-system related issue. Dirty injectors?, low fuel pressure?, Time for a new fuel filter ?

 

Thanks. I replaced the filter about 40k ago. I’ll grab another one and maybe some seafoam in the fuel.

 

Could be the torque converter clutch sticking.

*NO* Seafoam - use Techron.

 

Agree with Techron over Seafoam. Or any product with high concentration of PEA (polyether-amine) such as Gumout Regane, or Redline S1