The RPMs while I'm driving seem to jump all the time... It will be on 2 and then will jump to 3 and sometimes it will be at to and drop down to 0 and then back to 2 in a split second! Also not only that but my car doesn't want to start sometimes as well! I don't know what's wrong with it and nobody seem so know! Please help!!!

My first question to you would be .."Is it doing it all the time..?TPS..( Throttle Position Sensor ) can cause this and also an IAC ( Idle Air Control Valve )...

Could be Your ignition switch, If you have a lot of wieght on Your keychain..... the switch gets sloppy and it will do some pretty weird stuff while driving... Jiggle your keys at the key ignition..... and see If it duplicates the problem. Seems like it's Bogging down... Hope this helps. One of many ideas.

Check for trouble codes. You can get this done free at most car part stores.

vacuum leak usually increases rpm--the electrics got hurt from overheat--hav a data stream run-displays values of evry component-so u kno what parts are bad----private mechanic not a dealer- a scanner that uses factory gear not a 30$ tool sold in stores--the vehicle computer may hav an issue-a readout wont disclose it--so disconnect batt n see if problem clears or pull plug on computer and clean the pins--may reboot

TPS sensor and IAC sensor.

Loose wire or bad throttle body

Sounds like your gas guage isn't accurate. A fuel pump is not designed to draw fuel from the tank until it is completly dry. This is to avoid sucking up all the debris on the bottom of the tank.

its probably the Idle air motor. they always go bad on the 4g63.

rpms should be about 750, or 850 with the A/C on

The EGR valve sticking, loose wires, bad ground connections, dirty connections, fuel pressure dropping out, vacuum leaks, or any combination of several of these at about the same time.

make sure car hasn't jumped time