Hi.. I think the surging checklist and this forum is great.. I use it to help solve almost every problem that comes up.. maybe oneday I will run out of questions.... So I was experiencing some surging.. but have pretty much got rid of that.. whether it was a vacuum leak or whatever... "The first obvious step" was to check the computer for error codes..... which I did... and second step was to check the iac, tps, mechanical adjustment etc. but it says not to do this step until you have cleared up the computer error codes... As of now I have almost cleared up them all... except.. ordered a kit that comes with tab tad and egr vacuum solenoids.. so I think that should clear up those error messages.... I am getting a error 81.. which I am hoping when I receive the solenoids it goes away too. Now here is my problem.. I'm getting error 13.. which has to do with the computer not being able to perform the low rpm test.... Now I have cleaned the iac... and as much as I could inside the throttle body without taking it off and readjusted the tps again to .9 which was the highest I could get for now.. can try again.. got the car to rev with the iac unplugged down to 800 rpm.. .which is better than where I started 1500 rpm and surging... the surging has gone away but I don't understand why I can't get it lower than 800rpm with mechanical adjustment etc. and before moving on with the checklist it says to clear up the engine codes... anyone ever got error code 13???