My idle is about 1000-1100 rpms even after the engine is warmed up.
What would cause this?

Have you worked on the rig recently? A loose vac hose or electrical connection can do this. I had an 1100 idle for three months because the vac hose to the throttle opener thing on the front of the TB was sitting on the nipple, but not PUSHED on. Looked perfect, I only found it because I went to clean the TB to try and fix the problem. Once I realized the hose had been loose, I pushed it back on and...instant free fix. My favorite kind.

I have checked all vac lines, everything looks good.

I'm thinking IAC.

timing belt?

Check your IAC Valve. Happened to me weeks ago when finished replacing both head gaskets. Put everything back again and at cold start, idle was too low and then as soon it was getting hot, idle started to get higher till 1100 rpms. Opened and checked it and found it was stuck. Removed both the cap and plastic housing on both sides and after cleaning it, put some lithium grease and got it loose again. Now the problem is that the idle is not working fine. Sometimes it cold starts too low, sometimes is fine, same thing when engine is hot. IAC valves have their lifetime and mine already has 200,000 miles on it (have cleaned it for the third time). Can get a new one for $75 at rockauto.com.

Hope this helps

Mine's started doing this as well. Thought it was just the colder weather but now I have doubts. I understand the 1,000RPM idle when it's cold but it does it after warmed up sometimes. If I just pop the throttle a bit it comes back down to 650-700. Same issue? Might be time to clean my throttle body again.

Sounds like a sticky IAC. I'm guessing you can't blip the throttle like Jon can to bring it down?

No.

Sounds like your throttle body is dirty, lube the throttle return spring, too. If you plan on pulling the throttle body to clean you should pop the IAC and make sure it moves freely.

most likely not it, but. If you messed with the cruise cable at all lately make sure you have it back in the right orientation. It prefers to sit a convex angle if your looking at it from the front. If you pick it up and push it over to another angle it likes to settle (concave to you know from the front) it kicks your idle up to right about what your desrcibing.

Was that coherent? You guys get what I'm saying? I had a hard time describing this. It Happened to me once, probably not your issue but thought I would share.

I have removed the cruise cable, no change.
I have removed the IAC, cleaned it and tested it. It seems to check out but it didn't look like it closes all the way. I have a new one on it's way. I'll see next week when I install it.

Mine behaves better now but pretty sure at least in my case is the IAC. Sometimes the engine just doesn't start but if I press the pedal a little bit, then it just goes. One of the signals IAC's show when they're getting stuck.

A co-worker told me to check the throttle body, get it cleaned cause sometimes it gets stuck as well due to the fuel and dust residue that sticks to them. I'll check mine this weekend.

Did this start before or after installing the fuel pump!?

Last weekend I cleaned my mass air flow sensor (with electronic contact cleaner). It was super dirty and black. Then I used carb medic to clean the butterfly valve in the throttle body.

Mine actually idled higher (~1000) after I did the maintenance. I don't really mind it, because it's cold enough here I need it.

I think it could be normal. Does anyone know what a brand new 3rd Gen idled at in park?

Edit: I also changed my PCV valve.

I just got mine and when I fire it up it revs at 1500rpm! I guess I'll clean the suggested parts and see if it gets better

The engine revving as high as 1500 rpm when the engine is started cold, especially at colder ambient temperatures, is normal. If the idle rpm drops to around 700-800 rpm when the engine is at operating temperature, you likely don't have a problem.