My ford escape 2008 hybrid suddenly runs at higher rpms and idles at 1500 rpms. yesterday it worked fine and idled at 1100 rpms

If you do not have a check engine light on you may have an issue with the electronic throttle control system, repair requires the system be scanned to see why it is idling to high. If you do have a check engine light on have the system tested for fault codes.

The 0171 code is a lean condition defect. This means the engine is getting extra air from somewhere. Could be a loose vacuum hose, bad intake gasket, or something else.

Thanks for choosing FixYa and welcome to the site. I would say it is either the idle control sensor or the map sensor. Usually, with the map sensor, you experience the car stalling out. If this is not happening, I would say change the idle control sensor. If you have a check engine light on, take it to Autozone and have it scanned to make sure.

your idle position sensor could be bad. if it reads incorrectly, then it can randomly adjust to a higher idle like when you cold crank and let it warm up.

...and no check engine light? Could be a number of things. Start with a couple cheap things. Check the shart/large diameter vacuum hose on the back passenger sideof the engine. On top of the intake. Common vacuum leak.
Or get some MAF spray cleaner and clean the MAF sensor.

It is most likely you wheel alignment (costs about 20 bucks to have your wheels aligned) or try checking the tire Pressure to make sure they're all even maybe hope this helps

if it only does this when its cold its normal, the car is just setting a higher idle to warm up the engine

I bought a locking gas cap recently from Pep Boys. Maybe you can check online?

As for the noise.. I don't think I've heard anything like that with my 2008 Hybrid. I do notice lots of different noises but I tend to not pay much attention to them..