Surge then RPM's drop to about 200

Here's one for ya. When I come up to a stop light, sometimes the RPM's will surge up to about 800 then they quickly drop to about 300. The engine doesn't stall but I do have to push the pedal to keep it running. Any ideas?

 

O2 Sensor may be bad. Could be sending false readings thus affecting idle. Had that happen to me. I find that when I have had idle issues in the past its usually a sensor issue. MAF, O2,...something. Could be a fuel filter though it usually sputters and dies.

 

Throwing any codes?

Fuel pressure switch, fuel pump, fuel filter, dirty air filter, misfire at idle, bad alt, bad mad, list goes a on

 

Also might want to check your idle Air control valve. My truck does the same thing sometimes but I just haven't got around to replacing it.

 

Running lean, and even rich is crazy bad for your engine.....

 

Ya I know that why I haven't been driving it. I've been trying to order it off of a couple of Toyota websites but when I search for the part it never comes up

 

This^ it happened on my old Ranger. Does ur trucks rpm shoot up to like 2k when u start the truck? Or just at stop lights?

 

No the rpms just up to 1200 when I first start it up but drop down to 1000 till it warms up. Sometimes when I am at a light the rms will drop to 500

 

Today at lunch it idled at about 2000 when I first started it. No codes are being thrown.