I have a 1999 F 250SD V10 and with the AC on the engine will surge at ldle 5 to 6 hundred RPMs when the AC compressor comes on. Does not do it in vent mode of course. The PCV hose been replaced and the fuel pump has been replaced. Any Ideas?

 

Almost sounds like your idle air control valve isn't able to control the idle speed. I'd suggest removing it, checking it's condition, and cleaning it out with a can of brake cleaner.

 

You can clean the IACV whie on the truck with Seafoam through the brake booster vacuum hose.

I did this prior to replacement, worked temporarily.

 

double post

 

I will try this before I replace it. Thanks

 

Thanks for your help😀

 

Let us know how it turns out!