Hesitation/choking/surging/pinging when warm

My 2000 Vulcan pings, chokes, hesitates and surges a lot when the outside temperature is anywhere above about 0C. The warmer the outside temperature, the worse the symptoms. When it's say +30C outside, the pinging is just dreadful and when it pings it has zero power/acceleration.

When the temperature was -10C the car drove fairly smoothly, even when the engine was at running temperature. When the temperature was back up 11C it was pinging and choking as usual.

I've already had the injectors flushed and the PCM flashed to slightly retard the timing (for a TSB?). I'm hoping to get the spark plugs and coil pack replaced soon, but what else could be wrong that is dependant on outside temperature and/or humidity?

Thanks

Sounds like a Mass air flow sensor (the device between the
air filter and the engine intake) it should have given a engine code. The MAFs is what accounts for differences in the air density due to temperature and humidity. This output is used by the engine computer to calculate the proper spark timing and fuel amounts.

The check engine light isn't on.

Thanks