small cam idle in P/N issue - fine in Drive

[PilotEiser]

2003 Silverado 1500, 5.3 (LM7)
swapped with the Summit stage one cam (SUM-8718) to give it a little bit more for my daily driver/boat tower. Idle has been "hunting" a lot in P/N but stable in Drive, I adjusted the idle adaptive spark over and under by reducing it by 50% and that seemed to help but the idle is still "rough" in P/N while nice and smooth in Drive. I'm sure it's something little I've overlooked. I've searched here and elsewhere and tried going through the idle tuning process, but doesn't seem to help and most guides are for much bigger cams than this one or issues in drive. Any tips would be greatly appreciated. I did get a P0300 but reset and it hasn't come back. Also replace Knock sensors, timing chain, springs, valve seals, O2 (stock) sensors - really don't want to invest in adding wide band just to get a smooth idle in this one.

Cam specs:
Intake Duration at 050 inch Lift: 205
Exhaust Duration at 050 inch Lift: 217
Duration at 050 inch Lift: 205 int./217 exh.
Advertised Intake Duration: 258
Advertised Exhaust Duration: 270
Advertised Duration: 258 int./270 exh.
Intake Valve Lift with Factory Rocker Arm Ratio: 0.500 in.
Exhaust Valve Lift with Factory Rocker Arm Ratio: 0.500 in.
Valve Lift with Factory Rocker Arm Ratio: 0.500 int./0.500 exh.
Lobe Separation (degrees): 112

other mods include CAI, Magnaflow muffler (again, this isn't a race truck/car)

thanks for any tips
Happy New year

[Jeff7577]

Are you against raising idle to 750? Thats what I would do.

[PilotEiser]

Thanks, I will probably go that route but wanted to try and avoid raising it much more if possible (already raised it about 100rpm from stock) since it works so nicely in drive. However, if that's the only way then so be it.

also the .hpl attached above is 1 min idle in neutral then 1 min in drive then 1 min back in neutral....

[LSandlteditor]

PM Me if you have any questions and we can square your tune away NO problem. Id also increase the Base running airflow 2 grams to start, set up a custom PID list in the scanner and scan it for desired idle airflow

[2xLS1]

That cam should idle easily at 650 P/N and in gear.

[PilotEiser]

Thanks for the suggestions guys. I did add 2 grams of air and it helped a little but adding more did not. What's perplexing me the most is if I put it in drive, idles perfectly - back to neutral and it starts hunting again. It idles and will stay running, just hunts when not in gear.
Going into the scanner and the controls and special functions, Fuel then manually adjusting the Air-Fuel control i can get it to idle nicely, but when I turn this off it starts hunting again - even though the idle air is set the same. I've tried comparing with several repository tunes and can't seem to find differences. I've considered I got an injector or two dirty when i had the intake off, but it idles so nicely in gear. I'll keep plugging away at programming and mechanical and post back if I find anything.

LSandlteditor, I'll PM you to discuss tuning further. thanks.

[Zoboo]

Just curious if you found a solution. I have a 2002 Tahoe, same cam, same problem. I idle at 550 in drive and P/N. In drive its smooth, in P/N not so much. However, if I turn on the A/C it smooths right out perfect. In the scans I see the base airflow increases slightly and the idle stays at 550. I have adjusted the base idle airflow but it hasn't helped. I'm not sure if some other adaptive is preventing my adjustment from taking place. I am thinking I might need to try leaning the idle out...