stepper motors

[glider]

CJR, you're likely to get a better result from MikeHill's cleanout suggestion than just changing filters, but they need changed every 12000 miles anyway. They're not expensive from Volvo. If you're not technically minded, I suggest taking it to an LPG garage. One of the filters is easy, but the other is tricky. The garage who replaced my gas distributor said they used to leave the distributors soaking overnight in carburettor cleaner to cure the problems we all have, but there's no guarantee it works. Certainly worth a try, though.
Some BiFuel owners here suggest that a regular cleanout should be part of the regular maintenance schedule, and I would agree, as I have read of owners having replaced two or three gas distributors on cars with mileage only around 100,000 ( with Volvo picking up a share of the bill).