Clean TB, IAC. Check for vacuum leaks - cracked hoses, TB base, intake manifold gasket, brake booster, etc....

 

Also, off the subject. Shop is trying to tell me it takes 5.2 hours and $829 to change a ventilator actuator door...

 

I would never guess brake booster

 

The largest vacuum line under the hood supplies the brake booster. The diaphragm within can also fail and leak vacuum, but that usually comes with a drop in brake performance. Vacuum leaks often cause a high and/or rough idle. I'd hose the TB and IAC circuit with carb cleaner and flammable brake clean with the engine running, and keep blipping the throttle with each spray to keep it running. Avoid revving over 3k. You can also then use the same spray to hose down all the vacuum lines, TB gasket, throttle plate shaft bushing, intake manifold gasket, etc. I also agree with the above and dump a bottle of injector cleaner in the tank....

This is all a good, cheap, easy start before you start firing the parts cannon at it

 

You might try some injector cleaner.

 

I run seafoam through it about every 3 mo ths or so

 

What brand fuel pump did you go with. Did you replace just the fuel pump or the whole sending unit

 

The whole sending unit

 

$829 is a good price to change that door. The entire dash has to come out to do it right.

Assuming the blend doors are what actually failed here...there is another method that is a DIY called the "Heater treater". Requires some basic cutting of the area where the blend doors are located to replace them, then just seal back up the cut out area. A shop (especially dealer) might refuse to do it that way but there could be a mechanic that is willing to do it that way if you are unable.

I 2nd the try for an Injector treatment first. Techron is a great one to use. Get 2 bottles of it that treats up to 12 gallons and I would either add both bottles to a half full tank (about 11 gallons) or add each bottle to full ups of about 6 gallons each and run till near empty. Be sure to do this when you know you'll be driving it often and for longer distances if possible to improve the continuous cleaning action it provides. If it works and there is improvement, add a 3rd bottle to the next 12 gallons and then at (or just before) every oil change, add in another.

Depending on how many miles were put on since the last plug change, it could be time again. The copper plugs are specified so do not use anything exotic/expensive. The I6 likes fresh plugs and clean injectors. The regular 4.7 does too.
At least check the gaps on a couple of plugs to make sure they are in spec.

 

I fixed it. It ended up being the vacuum hose under the hood that connects was off. Replaced that hose with new and it works just fine now and saves me $800.

 

You might want to check the PCV valve and associated piping. IDK much about the 6 cylinder engine, but on the 4.7L 8 cylinder the hoses on the PCV tend to crack and rot.
+1 on cleaning the TB, AIC valve and checking TPS. Very important.
Hmmm, any codes?

 

No codes.

 

Welcome to the bad vacuum supply club.

still getting the rough starts? I’ve read somewhere along the line that these could sometimes airlock when hot..I remember something like number 2 or 3 was the problem.

 

Mine does that if I shut it off within the first minute of a cold start. It’s then hard to start and sometimes shudders.

 

Great forum participants and replies!!
Totally agree with TB and IAC. I have a 01 GC 4.0. You may also double check the TPS(throttle position sensor) contacts and wiring harness. I had some mild idling issues((compared to yours), I removed the throttle body and submerged it overnight in carb cleaner. I also disassembled the the IAC and found it loaded with gooo and black stuff-cleaned thoroughly and reassembled. New TB gasket and issues gone and signif improvement in acceleration.. Just as an aside, I smoke tested through a vac hose toward the TB and found a tiny leak at the TB shaft bushing- I didn’t replace it as I couldn’t find/buy a separate bushing.

 

^^^ That looks like this...

 

Yes!! My canister vac line was worse, Hahaha