S320 Engine trouble

I have a 92 model 300SE (S320) which is only used as a weekend car. It has pretty high mileage at 170K but generally runs like a dream. Recently it has developed a strange problem. On the first day of use after it has been sitting up for a week it starts to splutter and missfire after around 10 minutes running, just warmed up. Then it cuts out and wont even make an effort to start until you wait 30minutes and let it cool down. After which it starts perfectly and runs problem free for the rest of the weekend. The same problem will occur the next weekend.
This has been going on for the last 6 weeks or so. Last weekend I cleaned down the oxygen sensor and it helped a bit in that when running it was smoother and more responsive. I was hoping that all would be well this weekend but the same problem exists. Anyone have any ideas as to what the problem may be?

I have the same car you do but with 135,000 miles on it. I'm not sure if I can answer your problem but mine runs great with no problems. I had recently given it a tune up with new distributor caps and sparkplugs. Good luck.

Did you try to clean the injectors?

This will not fix but you could isolate btwn. fuel and ignition by spraying start fluid into air intake. If it starts its a fuel delivery problem. trouble shoot from there.

I think your car's problem is the fuel pump check them out since this kind of cars have 2 pumps.