When it's warm out side and I stop at a light it will rev back and fourth from 900 rpms to 1100 rpms in drive but if it's in neutral or park it will rev steady at 2100 rpms or just below 2000 rpms anyone know how to fix this or what's even wrong?
First, you should not run premium fuel in your engine. Higher octane fuels are harder to ignite, slower to burn, and thus are known to leave deposits behind in engines not designed for high octane gasolines. The ONLY purpose of additional octane is to make gasoline harder and slower to ignite so high compression engines won't prematurely ignite it and cause pinging or detonation. It adds no power and it definitely does not cause the engine to run cleaner.
Not to mention standard octanes like 87 have the same cleaning additives 89 and 91 octanes do, as mandated by the EPA back in 97 or so.
There is no upside to running a "premium fuel" at all, only downsides like unburned fuel deposits left behind. Really. The gasoline manufacturers like having that "mystique" about calling it premium since it's not really a premium grade at all, it just includes more octane that is not usable in a conventional engine like the 2.5L or 4.0L.
Your high rpms could be caused by a vacuum leak or a sticking IAC (idle air control) module. Sometimes by a bad TPS (throttle position sensor). Vacuum leaks are commonly caused by an old split/cracked vacuum hose. Sometimes by an intake manifold that wasn't quite seated properly which would allow extra air into the engine.
__________________ When you have a choice, buy American.
You can spray carb cleaner or starting fluid on your lines to see if RPMs go up. To check for leaks. If your parents drive Porches or some other high compression vehicle it may be in order. For Jeeps no way. Waste of money. It will say in the owners manual. Like my r1 4 cylinder 186 mph bike needs premium. High compression. My Jeep Id feel like I'm giving it slug gas since I know better.
It only happens when it is warm out side like 60 and up so that really confuses me
That points to the TPS. Above idle, the IAC opens fully. If the PCM doesn't get the signal that the throttle has closed, it doesn't attempt to control rpm through the IAC. An open IAC will typically cause rpm's in the 2000 range, with the throttle closed. TPS failures are frequently heat related.
You can check the output resistance for smooth change as the throttle opens/closes. That's not always conclusive, however. On some applications, unplugging the TPS will result in an immediate rpm drop to normal if a high rpm condition exists at the time.
It's also possible that your IAC is sticking. Cleaning the pintle would not be a bad idea in any case.
In place of the "Premium," gas, I suggest using a gas additive and lower octane like 87 or 89. the gas additive will ignite the fuel evenly and cleanly. It will also help to keep the fuel system cleaner by breaking down any deposits already there.