It's been over 100 degrees in my neck-of-the-woods for the last week, and let's just say that a 23-year-old retrofitted A/C unit is hardly a match for that kind of heat. Anyway, my real problem is BUCKING under acceleration. This only seem to happen when it's hot--I never experienced any bucking all winter, though I had during the previous summer.

The car is an 82 240, with a wonderful k-jet. It bucks as if it's losing fuel, kind of like when you're running out of gas, but harsher. The car has idle problems too (stalling when hot), but that may or may not be related. Like I said, this bucking problem only occurs when it's hot and you've been driving for at least 5 minutes. Usually. It can happen in any gear (M46), but it is most likely to attack when shifting into second.

It definitely frightens my passengers, but the usual riders have gotten used to it and aren't too freaked out.

Could it be...
1. Electrical problem? This never occured until after my last tune-up, but I don't remember if it was immediately following that operation or not.
2. Fuel delivery problem? The bucking is just as likely to happen on a full tank, so that makes me wonder.
3. Temperature sensor? I've only just heard about this.

Thanks in advance for you help.