Hi all.
I have a weird intermittent problem.
Nomally there is nothing wrong with the engine. It starts, drives and drives and drives. No problem at all. And I easily drive over 20000km a year through the whole of Europe.
It has almost new ignition with bosch distributorcap/rotor, leads, ngk irridium plugs. New bosch benzine/oil filter and new Shell 5/40 full synthetic oil. Original Airfilter is clean.
BUT Sometimes, out of the blue it get's the stutters for a few minutes. And when it is gone, it stays gone. Sometimes for months.
It only seems to happen when i am just waiting at a light, traffic jam or just got started.
When it happens the benzine usage meter goes way up to 50 or just under it.
It will rev more slow and harder to get up. Also pushes out a bit of unburned fuel smoke from the exhaust.
When it stops, the meter goes to normal again, smoke is gone, and the whole problem is gone.
It happened about 3 times now this year.
Maybe related
Last summer it was increadibly warm, 40+ C and it had starting problems when parked uphill. Had to crank for a really long time (minute in two three cranks) before it would finaly start. Did a lot of crappy clay, gravel, shocky up/downhill roads that summer.
Actually do that every summer and 4 other times a year. Its the road to a Holiday house
Since I drive a lot. I probably have to say that I drive the car until the tank is empty. So only when the computer sais 20km more to go, I tank.
I dont tank expensive additive benzine. Just normal plain cheap european 95 octane. I stay far away from e85 or what the french and germans sell as 95 plus 10% ethanol.
I noticed no difference in performance or stutter when trying 98, 100 or 102 octane, wich is very affordable and everywhere availlable on my many trips through Germany.
And as we all know, you can actually test that difference in Germany.
Driving the Volvo well over 200km/h is really not at all strange to me. Or hunting some fast audis or bmws through traffic for some time. And other times I just do 120km/h on the CC to save benzine. ahum.. well save.. It still does almost 9L then.. 
I never ever seek the rev limits or push it too far. Never had the stutter at speeds.
I hope someone can give me some advice since I want to get an LPG setup. And therefor I want it to be as perfect as possible.
Thans!!
153k