2000 6 cyl rodeo surging idle

i have a 2000 6 cyl rodeo with 85000 miles on it. And check engine light came on and bought new egr valve after using brother hand held machine for checking code.The truck surges from 0 to 1000 rpms and keeps stalling. And then at other times seems fine. I took it to autozone and they checked it and said i need a dpfe sensor. Which i dont even think there is one for the truck. Anyway autozone didnt have the part and told me to go and pay for dianasos with big machine for 90 bucks. Any one have a simular problems or any ideas.Could this be an idle air sensor or map sensor. I dont have a lot of money to throw on a machine to test it and then for the part. Anybody have a good idea what it night be? thank you

If you have a harbor freight in your area you can buy a code reader for 40 bucks.

Autozone typically will read codes for free.

99.9% of the time your issue is caused by a leaking intake manifold gasket (I've had mine replace 2x under warranty within 70k).

here is the details on it:

http://isuzufaq.ibctech.ca/#faq5

The dealer typically charges 350 to replace the gaskets.

If the issue is not a leaking intake manifold gasket you might want to replace the Idle Air Control sensor. I had to do that even though I did not get a code for the IAC. That solved my idle/stall issue.