unfortunately this is going to take some time & driving on your part.
drivability issues are difficult.
you need to take into account all conditions at the time the concern occurs.
1. Look to the instrument cluster. ( you said that there were no warning lights or gages fluctuating)
2. Listen to the engine ( you said that there was no odd noise & the rpms did not fluctuate, but the engine tried to stall)
3. What are the outside conditions ( you said it was raining ) Was it very windy & if so, what was the wind direction ( this is odd, but it can make a difference )
It is possible that the cams are off by a tooth, but you would have a light on.
I suggest taking it back the the shop where the work was performed & have them check it out with the scanner.
Do not accept this answer until you have done the above & reported back with further info.