An air mass meter "generally" messes up when cold, not when warm, UNLESS you still have your preheat hose hooked up to your air filter box and your air filter box thermostat has failed. You have a funky looking, looks like it belongs in your home duct work instead of your car, hose that runs from your exhaust manifold around to your air filter box. This is to prevent icing up in northern climates, and aids in a quicker warm up period of your car. The problem with that is the air filter box thermostat. When it reaches a certain temp, the air filter box thermostat opens a fresh air vent, and the now too hot air is released under your car instead of through your rather expensive air mass meter. If this part fails, the too hot air now goes through your air mass meter. Try unhooking that ductwork style hose and see if it helps. Hopefully the air mass meter hasn't been cooked.

Next, check your connector to your crank sensor, and make certain your 10mm bolt hasn't wiggled free somewhat.

Last, a power stage will also cause a similar problem, as the spark will become weaker the hotter the car gets. This component sits on your inner fender on the driver's side. Make certain it is securely grounded on the fender, and that the connector is clean.

Chris