Ossy, got your answer for this one...had the exact same problem. You need to remove the #5 fuel injector rail and reseal. My mechanic charged me $57.00 for a set of fuel injector seals. The first step he did to see if it was to put in fuel injector cleaner. We left that go to work for about two weeks. Still having the problem, then put the new seals on. That was about 3000 miles ago and haven't had a problem since. Runs beautifully. He also removed and replaced intake manifold gasket. (I really can't remember if that had anything to do with the fuel injector problem, but it was on my invoice so I thought I'd mention it to you.) I read many, many, many forums with LHS's and this problem. Alot of people had costly repairs done and it still wasn't working. A couple people mentioned this fix and like I said, have not had another's day problem. Hope this helps.