1) The easy one if you pay attention to JM's post last week. Perfect running car, '83 242Ti, when warmed up and parked for ~ 30 min., subsequent restart is reluctant to catch. Long cranking and poor idle for a couple of seconds. What do you look for and swap? It takes about 10 min. but it can be messy.
2) 244Ti runs strong for 5 minutes when cold started, then starts a miserable stumble at full boost. Definitely heat related and definitely boost limiting. This one was solved by remembering an old British Volvo club tip that was kindly pointed out by a Brickster long ago. This one involves a part that all of us will deal with over and over.