First off, how do you know what you are idling at? There is only 1,2,3 etc on the RPM guage... So how do you know when its at 650,675 or 750. all I can see is my needle is sitting at the notch in between 0 and 1. Is that notch 500 or what? Mine sits just below the half notch and it bounces just a little below that unless the fan kicks on then it sits right on the half notch.
Second if you are having a heat soak issue or a missfire, try and take the fuel rail off and clean all your injectors. If the TB was that bad, I can only imagine what your injectors look like, replace the o-rings while your at it. Running some injector cleaner might help but I think taking the time to remove them and actually clean them is even better.

My 89 4.0 does the same thing. It starts up beautifully, idles really nice for about 10 seconds, then starts to have a jumpy idle... its not that its rough, its just like it can't decide what rpm to idle at so it just jumps around? I have neon injectors, and it helped a whole lot with the low idle, but the jumpy idle is still there. I just rebuilt it around 4 months ago, and when i did i cleaned and polished EVERYTHING! so no carbon in TB, or intake manifold inside or out. and obviously the head was machined, so no carbon in that or anywhere else in the motor, so i don't think carbon build up is the issue. It even had the jumpy idle even before i rebuilt it, so its looking like its either a normal 4.0 thing, or maybe something weird in the fuel/ignition system? I have ran a bunch of fuel cleaner through, but didn't really help. Like i said, its not like its running rough, its just not running at a constant idle.

So if anyone figures this out, i would love to know how to fix it...

Thanks, it seems to be the same from what I am reading. I have read several guys say their XJ purrs and I think mine idles pretty darn good, it just has the occasional jumpy feeling like it is trying to kick itself up a little and then drops back down. I am just going to be thankful it starts every day and no check engine light.

If you have A/C...could just be your hi/lo switch on the A/C system shutting off and turning back on....mine does this - goes away if I I shut off the fans competely

Thanks for responding! I am just estimating the idle. Either way its idling too low.. With AC on it purrs.. I was going to put thos BOCHE injectors from ebay.. from those guys in FL they cost 119.00 on their website with 4 holes on there.. What do you think?

Go to a JY and grab some 703s out of a neon. Perform just as good if not better than the bosche.

Single Hole Better then 4 Hole Injector by Ford? Please LOOK!
 

:excl:Look at this about injectors: http://www.ausjeepoffroad.com/forum/...ad.php?t=92236

I just bought the Ford Mustang Injectors: XR3E 9F593 A4B which according to these guys is the best one and its SINGLE hole.. What do you think? You have to read the link.. I have a 2001 so I need EV6 - 703s wont work since no UCAR..

4 holes is superior to one, for your year though, looks like thats your best option.

I just installed the Ford: XR3E 9F593 A4B Motorcraft Part Number: CM4956 for my 2001
 

I just installed the Ford: XR3E 9F593 A4B Motorcraft Part Number: CM4956

for my 2001 Cherokee 4.0L

I DID NOT REMOVE FUEL RAIL
THESE INJECTORS DO NOT USE THE STOCK CLIPNUTS

I completed the job in 1.5 hours start to finish. A monkey with a screwdriver and a pliers could do this job. I DID NOT remove the fuel line from the fuel rail. I was able to rotate the rail a bit upward while connected to fuel line and I removed and installed the new injectors.

The truck runs smoother at idle. Its quick as all hell but it was before as well since I ran that seafoam crap.. That stuff works man!

Anyway, I see very little difference.. At least they work and apparently according to that post at http://www.ausjeepoffroad.com/forum/...ad.php?t=92236 they are the best ones.

I can assure you they work for my 2001 without clipnuts and its an easy job!! DO IT!! You can buy them on the company website as well for 60.00!! Look em up on eBay..

I just spoke with http://www.mrinjector.us/ Bill.. I bought Filters and O rings for my stock units and for some used injectors Boche 784's that are on the way.. He told me for this style Intake spray pattern is not critical if not relevant at all. Thats why Jeep kept using these injectors that shoot gas like a water gun. Spray pattern is critical in OTHER applications but not on the 4 liter because, according to Bill, this style intake will put gas in a READY mode for use during driving and that gas can SIT inside the motor/ head/ cylynder until its used.. So spray patter is meaningless.. Somehting like this he told me.. Im no motor genius.. These guys have all the rebuild parts for the stock injectors. Anyway, I now have in my possession the fords stated here, I have 2 sets of stock injectors that will be refurbished to new, and I have a set of 784's that Im rebuilding with new rings, filters and caps, I will also be ordering the c4b's. When I am done I will have mileage specs on ALL 4 sets of injectors.. I will run two tanks out on each style to see what gas mileage I get.. When im done the results will be exacting.. Right now im lucky to get 15mpg with these fords Im running as stated in this thread. By the time Im done I will have spend hundreds of dollars to rebuild and buy injectors.. So much so i will begin to sell them off.. I even bought a Jewlry cleaner to clean the tips. lol.. All in the persuit of better gas mileage.. Im starting to spend so much on injectors that I wont make it up on gas..