My 1998 V70R AWD has about 44K miles and has always been serviced by the local Volvo Dealer. The first "check engine light" was due to the gas cap being loose and since then I have always carefully tightened the cap. The second occurred shortly after a 42K scheduled sevice during which the air conditioning system was also serviced. The dealer "traced the problem to the canister purge valve" and replaced it. Since then the engine has occasionally stopped running at stop signs and stop lights, but can be restarted immediately. I just returned from a 900 mile trip during which the light came on and stayed on just after decending a long hill at about the 800 mile point. I have not yet been back to the dealer and will appreciate any ideas about what is the problem and what should be done about it. Thanks in advance for your suggestons.