That's right....edit to post 19. Corrected DTC's in bold.

Missed the OP's typo post earlier...Thanx for pointing that out BB.

IMRC - Runners on both banks are open, cannot close.

Inspect vac line mini-tube harness/confirm solenoid function.

 

OBD codes beginning with 0 must have a universal meaning. P0171 means the same thing no matter who made the car.
OBD codes beginning with 1 are manufacturer specific. They can have different meanings, depending on who made the car.

 

I figure this is the best thread to clear some stuff up for you.

You have a single electric IMRC actuator just like the 3.8, the 3.9 liter Ford V6 engines. The actuator has 2 rods that actuate 2 sets of butterfly valves in the intake manifold. The rods snap into the actuator and the manifold using a grommet/bushing. Usually the bushing/grommet on the intake side breaks first and allows a rod to fall out of the intake side but stay attached to the actuator. When the actuator attempts to move the rod, it can't because the rod is jammed against something. This is when you get the DTC. Your actuator is probably fine, it's just the bushing than needs replacing.

I'm attaching a video of some dude with a Windstar that has the problem I described. The IMRC system is much easier to see in a FWD application, that's why I didn't look for F150 videos. In this video, the rod is moved all the way inboard. You can see by the way the rod is laying that the actuator cannot move the rod outboard at all because it's laying against the lower intake casting.

 

What's the difference between 97-98 and 99-04?

Seems like you're talking about 99-04. I keep reading about solenoid controlled vacuum valves for 97-98. 99-04 are the electric motors. Are you saying that the Rockauto picture is an electric motor? Looks like a vacuum actuator
.

 

The only 4.2l motors that I have ever seen have problems with IMRC have the electric ones. Early 4.2's did come with the electric ones. An image search will confirm.