Stian- This could be way off, but something very similar happened to mine. If you have ever looked at the configuration of the fuel pump/boot area also sits directly below a water drain in the body. My situation was this, and it's possible it's also yours. The rubber cap on top of the fuel pump boot which keeps water away from the pump itself is very, very, very hard to get back on top correcly, and they had not only left the boot cap too high off of the boot, but they had also not seated the pump itself far enough into the boot, so when it rained, water got into my fuel system, causing very similar problems. Seeing as they washed it before you picked it up, maybe you should check this out. Scott Download NeoPlanet at http://www.neoplanet.com