I have a '96 vtec with a '00 h22a vtec swap in it. It hesitates a little at start ups, but starts just fine. It'll idle perfectly fine at start up, but whenever I apply just the slightest amount of gas, the RPM's will go up and down between 1-2.5k. I've scanned the ECU and I got a P1491 and P0135 codes. I've cleaned the EGR valve and the IACV, but nothing has changed. Any suggestions? I'd really appreciate any help I can get. Thanks.

 

Sounds like you need to replace your iacv.

 

look in the FAQ thread in this section.