The car: 99 OB wagon, 5 speed MT, 209k miles. Both O2 and knock sensors replaced around 170k miles due to failures that threw codes. Plugs and wires also replaced at around 170k miles. MAF replaced with good used one around 190k miles. No recent check engine light or codes.
Twice in the last few weeks the car hesitated, by which I mean that the car had barely enough power to keep moving. In both cases the engine had only run for 1-2 minutes after a cold start on 85 deg F days. The first time I was going 30ish mph when it occurred, then the car slowed to 20-25 mph and could barely keep going for about a minute, then the performance recovered. The second time I was leaving a parking lot with several stop signs, and the car could barely get out of it's own way. This incident lasted 1-2 minutes.
My first thought was the fuel pump which I believe to be original, but after some searching I've seen references to engine temperature and a few other sensors.
So, I don't want to start throwing money in the form of parts hoping the problem doesn't come back, but I also prefer to not get stranded. Being rescued can be expensive too.