2002 sebring sudddenly will not rev over 1500 rpm

Nothing, you have hit the rev limiter. The up and down is the computer controlling the rpm. If you drive it, it should rev past 3,000. The computer is designed to keep free wheeling rpm to that level. It will only allow a higher rpm if vehicle is in gear and moving with a load.

I’m happy to help further over the phone at https://www.6ya.com/expert/david_c087e4b7d13c0163

http://www.kia-forums.com/1g-2001-2005-rio/49008-2004-kia-rio-starts-idles-but.html

The PO 316 is still misfires om first 1000 revolutions
so the shop did a poor job for you on resolveing the
cylinder misfires

Try a diffferent shop

Have to clean the MAF Sensor & replace upstream
oxygen sensors if over 100,000 miles

Need the correct oem spark spark plugs/any brand

No reason the gas filter should be clogged unless it was in
the car for 10 years

Fuel pressure should be checked

Need to check for cylinder misfires on a road test of 20
miles or more with professional software in Mode#06

Because you disconnected the battery you lost the long trim value,you will now have to relearn the idle,start the vehicle idle it to 1500 RPM,hold for a minute,idle should stabilize,turn on A/C let it idle,for a minute,now your done,

It sounds like it is working backwards. Around the time your truck was made the industry had different emissions standards for trucks and cars. There were less controls on trucks.

There were vacuum controls that would increase idle speed when the engine was cold. The way this was done is through a water temperature sensor that is commonly called a vacuum tree. It is called a tree because it is shaped like a tree trunk with a few branches and each branch has a vacuum hose. As water temperature increases the vacuum routing changes. The cold setting makes an idle step-up dash-pot raise RPM and close the choke plate. As the water warms, the internal parts of the vacuum tree move and change the vacuum ports.

When the ports change, RPM drops and the choke plate opens and low idle speeds are restored. With the choke plate open high speed operation of the motor is assured without bogging down.

I would say most of what can be wrong is cheap to fix. A new thermostat, perhaps a new vacuum tree. Your problem can also be the vacuum lines are not connected to the correct ports. One thing many people do is to adjust the idle speed at the wrong time. The step-up cams are not in the proper position and when stuff starts working everything is out of adjustment because the changes were made at the wrong time.

This is a job for an old school mechanic.

It is possbile that you may be low on freon in your pickup and you may need to have it recharged this will run you about 60 dollars.

The computer will gather data as you drive it normally at various speeds on the highway and in town.

If the idle continues to not hold at the specified rpm then I would check into the iacv or idle air control valve being non functional or having dirty passage ways.

750 rpm?

your revs are too low.

The engine speed drives the oil pump via the timing belt.

too low revs = poor pump speed = low pressure.

I'll bet when you rev the idle speed faster, the warning goes off?

This may been an ignition module or a MAF sensor, this car may need to be diagnosed using a OBD I computer code reader to accurately diagnose the problem.

how about highway driving will it cruse at highway speeds and if you were to step down on it does it bog down ? and does it still have the cats on it ? just a thought..