So, this morning on the way to work, my 98 Ranger (2.5L I4), started to
surge badly when given any gas. It idles fine.

When given any gas, 1/3rd to full throttle, the engine surges between
idle and 1900-2200 rpm.

Checked the throttle cable, it's working fine, there are no obvious
physical problems. MIL doesn't come on, at any time, PCV valve rattles okay when shaken and was fully seated.

At this point, I could use a little guidance.

I'm assuming this is either:
- Fuel filter or pump, it's getting enough gas to idle but not any more.
- Mass airflow sensor
- EGR valve or idle control valve maybe?

Am I on the right track here? Any suggestions? Anyone dealt with this before?

 

Could a throttle position sensor also belong on the list?

My Idle air control valve went when I was driving and it was stuck idleing at 2000 rpm. If it was your idle air contol vavle i think you would have an idle problem

 

i would check the egr valve it could be stuck closed mine got stuck open and surged at idle

 

might have a vac leak. but check the others first, their a whole lot easier to fix than the vac leaks

 

check your fuel pressure

 

are you throwing any codes

 

Did you ever find out what the problem was? Mine started doing the same thing?