When re-setting the tps I can't get a constant reading at closed throttle.

Set tps to .540, Open throttle and get 4.2, close throttle and get .538, open and close again and get .547, and again to get .540. etc. Each time will get a different reading at closed position.

Is this normal to fluctuate that much and will that cause idle issues?

 

are you shure you are getting a good reading on the multi meter?

 

Sounds fine to me. That 3rd digit to the right of the decimal point is WAY down into the noise. You don't need that much precision. The 2nd digit can vary by a couple and it not cause a problem; let alone the 3rd one.

"Measure with micrometer, mark with chalk, cut with axe"

 

I checked with two different meters, same responce. Would this fluctation at close throttle effect the way the ecm signals the IAC? When the rough idle starts to happen, if the car doesn't stall, after 10 to 15 seconds the idle will pick up to around 750/800 and then flucuate from there back down to 500. It will do this untill you either shut down or take off down the road. Off idle it runs great.

 

Your TPS is fine.

 

As Sofakingdom said that slight variation in voltage will not cause a problem. Your problems are more likely caused by a bad or dirty IAC, I'd check that next.

 

Mine did exactly the same thing when I set it and I have no idle problems whatsoever.