Someone on the other site brought back a post from 2007 that includes one very creative owners ideas to address his particular stalling issue; hit the site, perhaps it will be helpful.
Thread is titled:
The 355 'spider' idle stumbling problem is solved!!!!
Grace and peace,
I took his advice and concentrated on the blowback from the fan (left side). Instead of modifying the radiator with shrouds, I simply isolated the top air duct (behind the door, and now the top duct is for intake
only, whereas the lower 3 are to cool the radiator. ) Ferrari made a mod to the duct for 1998 and newer 355's, and I more or less copied the mod, though they basically have 5 slots instead of four. Their mod allows less airflow to the intake, where mine allows slightly less airflow to the radiator which, in my opinion, runs relatively cool, as does the car. I have yet to go above 195 in this car, if that. We will see what a hot summer brings.
I used Duct tape, very durable plastic, which is almost impossible to rip by hand (an old drumhead from my DW drumset...very durable). I cleaned up the visual with carbon-fiber tape, and it looks great, actually.
3 test drives later, the car has yet to dog-out on me! Quite pleased.
Wasn't the fan or fan motor
Wasnt the fuses or relays
Wasn't the alternator
Wasn't the battery
Wasn't the charging system
Wasn't the sparkplugs.
It was the blowback of hot air... from the left side fan.