I have a similar situation sometimes when I try start my 99 NA V70. Usually it fires right up, so I'm used to giving the key a twist and a quick release and it's running. The problem occurs when it fails to start and I try again. At this point, it is VERY difficult to start, and if it does start, it is VERY had to keep running. If I baby it and pump/feather the gas, I can limp along until it finds its way. It's like the computer is trying to figure out what it is supposed to do. Come to think it does sound like a fuel problem, but it doesn't seem to be heat related.

Sounds like fuel pump relay. It is under the fuse box cover. The one marked 103 on top. It is not an expensive part and should be replaced as PM. The symptons you describe perfectly match its typical failure mode. However, I would not rule out leaky injectors or a bad (or dirty) fuel pressure regulator.

Good luck!
Icelandic

The new coil didn't hurt, you would have probably needed one sooner than later.

You might have a leaky injector, fouling your plugs and causing the no start condition. Next time you are at home and the engine is still warm, try to recreate the same condition. Immediately pull the plugs, looking for a wet one. I suggest taking the cover off before you start on this quest, it will save time.
If it has been a while, clean and regap the plugs or replace them.

Klaus
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Please answer, we need to know if the advice is good or bad. The 164 has a new home, all I am left with are 2 turbos :)

Hi Dancer,
Let me guess, if you let it cool down for @ 5 minutes it will start?
If this is the case, then I'm almost positive that it's your fuel pump
relay. It's located beside the fuse panel. When these relays get old they
become very heat sensitive. Cost about $40.00, plug & play.
FYI, on a really hot day it can shut down while driving - very dangerous
on the freeway!
Let me know how it goes.
Armie
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Luck favours the prepared.