Engine stalls when the transmission is shifting to park?

Yes, it does have 35,500 miles. I've been chasing this issue for some time, with two separate tuners. My new tuner had reviewed my logs and explained my fuel trims looked perfect. He sent me a new tune which I believe increased the idle RPMs, but the issue is still there. I just find it weird it only ever happens when shifting to park.

I forgot to mention it also has a cold air intake that I installed myself, if you think that might cause the issue maybe?

Yes, it has a thermostat and the IAT is integrated into the MAF from my understanding, which is installed in the new intake. Another possible culprit I'm researching is the obvious, the P0420 and P0430 codes for the O2 sensors reading below threshold. I do have headers and high flow catalytic converters, but maybe the car is adjusting AFR because of it? I'm considering using spacers to give distance to the downstream O2 sensors to see if that helps. The only reason I want to try is every time I attempt to datalog the issue it doesn't happen. But when it starts again usually the CEL follows the next day, which I just use my handheld to clear the DTCs.

Me again!
Over the weekend I tried the spacer trick, CEL and codes are now gone and for a couple of days I believed my issue was resolved. However yesterday I found out that the issue is still present. I'm currently waiting for my tuner to review the log to give me some feedback. I'm baffled by this, because it only happens every so often after the engine has been driven and is warm. When it does happen its bad, I can usually tell when it's about to happen because after I put the car in park it's like everything goes silent before the RPM surge, and I have done a lot of exhaust work so it's noticeable.

Tuner said he noticed some oscillation in spark. So, he sent a new tune to help with the issue. It worked for about a day and was right back. Called him and he mentioned that the spark plugs could be the culprit, and driving a V8 engine in Arizona weather probably doesn't help. So today I replaced all 8 spark plugs, so far so good I'm sure the ECU might be relearning after everything so I'm going to give it a couple of days and report back.

Thank you! Just an update, it was not the spark plugs, battery, or alternator. Had the plugs replaced with brand new OEM ones and the battery and alternator checked everything was good. I broke and decided to just take it to a shop so they could run diagnostics. I'm tired of chasing the issue, lol.

Good morning. I still haven't found the issue lol. Some new information, when I put the car in park the RPMs do search a bit, but today when I turned the A/C on after putting it in park it almost completely stalled out. Any ideas?

Both shops said they couldn't identify the issue and just offered to change the oil. I will be double checking the throttle body this weekend. I switched to a third Tuning company recently and the issue is still present. My first suspect is the throttle body, second is the voltage regulator, part of me believes it's an electrical issue, mainly the TB thinking adding extra load like the fan and maybe the TB is malfunctioning, or the voltage regulator is producing weird patterns. The search will continue, lol.

I think so. I decided to just clean my MAF and throttle body this weekend as well as check all hoses. I have the JLT II cold air intake. I guess the grommets were not the best quality and after lightly removing the connector this grommet split in half. It was in very rough shape. This is to one of the PCV hoses, so I believe it was a small vacuum leak.

I'm not sure yet I'm looking for replacements currently that will seal properly. I'll report back in a few days.

Hello, I am finally back with an answer to my issue. I've replaced a bunch of stuff and finally given up lol. After extensive research and thinking, I believe my issue is the cold air intake. The intake I have is open with a heat shield that blocks heat from the engine but not the front of the car. I also live in Arizona where temperatures are above 100 most days. What I believe my issue is, is the heat wash from my fan blowing at the intake filter causing an increase in the IAT as well as turbulence inside the intake and around the MAF. It makes sense in my head because after going into park, the car does not have outside air blowing to cool the engine and instead now relies on ambient temperatures, under the hood temperatures, and the fan blowing the hot air at the intake while in closed loop causing the car to adjust the fuel to be leaner to compensate and thus causing the surge. I'm no expert so please let me know if this doesn't make sense.