New user needs help

Hey folks-

Yet another episode of idle issues unresolved.

Ready for the rubber room.

New L92 416" stroker.... new NW 90. TH400/ss3600 verter. Trying to nail down the hot idle in/out of gear.

Showing a PO121.

Car will be rock solid at it's 950 rpm desired idle at start up and until warm. Surge happens after coming from part throttle to a stop. If put into P/N it will jump to and hang at 1500 rpm.

Also will surge badly(to the point of stalling) off throttle/foot on brake in drive at parking lot speeds.

Have had efilive for about a year or better, but haven't used it for anything but scanning and the real simple stuff so far.

Thought maybe was/is a decay issue as it also wants to do the cruise control effect after highway speeds off throttle.

Also, it seems the tune shows the P/N- in gear desired idle numbers are different during riseing ECT's Car was an M6, now A3. PCM shouldn't be recognizing a difference between P/N- D should it, and should these desired idle numbers per ECT's be the same in P/N/D?

Not sure where/what to look at/tweak to help current issue.

What "should" the IAC counts/voltage look like at warm idle?

What "should" the TPS voltage/position % look like at warm idle?

Any help/thoughts/advice or how to's would be greatly appreciated.

Thanx guys-