Volvo 1992 GL non-turbo 200+k miles Automatic, purchased new and has for many years been hard to get started and maintain idle with > 85-degree weather. Starts fine but need to pump the throttle some before it will hold idle, or will die. After it runs a few minutes it is fine. No problem in cooler weather. Saw Scotty's video about Mass Air cleaner thinking maybe to try, but am fearful of damaging the Mass Air sensor as they are very expensive and this is an old car.
Sounds like the cold start circuit maybe still activating when hot. Do you get any black smoke out the tail pipe when you have to pump it to keep it going? If so, too rich.
No, no black smoke. I always thought it was a vacuum lock or it needed colder gas before it would hold idle.