killymcgee

I'm at wits end on a 98 F150 4.2 that has a vacuum leak (i think). When accelerating hard AC switches to defrost. I also have IMRC codes for both sides and a stutter on the low end. My vacuum canister holds a vacuum, I replaced the PCV valve and hose (which had a hole), replaced the collapsed elbow on the bottom of the throttle body and patched 1 of the lines on the passenger side fender well (2wd) like you did but still have the same issue. I also tested the operation of the IMRC valves with a vacuum pump and they move freely and linkage is operational. Lastly I tried carb and choke cleaner method all over the motor (was kind of hoping the truck would burn out of my frustration) and then used a smoke machine pumping in dance room style smoke into the throttle body in hopes of seeing it escape somewhere. So the truck doesn't get driven.