2V idle hang up and low speed surging

[mybckup]

Howdy all,
Finally was able to see Diago last Friday to have my dyno run. Which turned out pretty good. Diago try a few times to squeeze all he could and well the little 2V n/a would only put out 298.4hp to the wheel, she just would not give the even 300. Oh well that's still about 340ish at the crank that is a nice gain from the stock generous 265 Ford gave them. Very happy with what Diago got out of her.
But of course the whole he ran it would idle just great but by time I reached the 401 and traffic the odd time it would idle at 900 then next stop it was up to 1300 then 3rd time was down to 600. After a long run up the 412 to 407 and back to Brampton smooth as silk. Off the highway idles fine. Saturday again runs great to Hanover. On route home Sunday would be all over even the odd time stalling.
I know the IAC is new as for replaced before motor rebuild, unless it was a defective. Someone mentioned maybe the EGR could be sticking. Seems like it is most noticeable after long drive. As far as know the EGR could be 23 years old. But as a dealer tech we used to just throw a new IAC on and Bob's your uncle. Customer happy and move on.
I am a looking for any other possibility or try what has worked in past.
Anyone have a thought or want to throw a dart at the board of possibilities?

[ZR]

IAC, unless OE Ford would replace.
As for EGR, not uncommon for controller to fail / partially fail. To test, pull line from the EGR valve and plug, test drive.
On a side note, many of the aftermarket TB's are prone to exactly as you've described.
How you doing?
Congrats on the tune.

[mybckup]

Doing well sir.
I was surprised at the results of the dyno run. Diago did a few tries to get the even 300, but not to be. That's ok I am happy with the results. Next is the suspension to do. I have all the parts just need to tear down and install. That will be known as phase 3. (motor, dyno , then suspension) Oh yes, the vibration I have been chasing since I bought the car was fixed by replacing trans mount. Thank you for your help on that.
As long as work doesn't get in the way anymore this week I'll try the EGR test.

[ZR]

^ Happy to help.

[Zee]

Beautiful ride.
I cant wait to get my car tuned!
Loving the Fr500 wheels.

[mybckup]

Ok so finally had a chance to dive into my issue to find the IAC was toast.
Managed to rebuild my suspension with Billsteins, rear upper and lower control arms and springs. Wow what fun ride now except for the erratic idle. Pulled the IAC to find a spring on the wrong side of the diaphram holding it open. So replaced with a new one and tweaked the throttle and TPS and bam Bobs your uncle.
Now all we need is good reliable weather to be able drive a little more often.

[ZR]

^ Nice, good to hear your enjoying it.