Don't know if this belongs here or in the Garage.

I have a nagging problem that's driving me insane. My work van, a 2005 Chevy Express, started misfiring a couple of weeks ago. Seems to happen every now and then, especially under load. My mechanic hooked it up to his scanner which revealed cylinder #8 as the culprit. What he can't pinpoint is the exact cause of the misfire. He's been going through the usual suspects: spark plugs and coils, but those didn't solve the problem. Now he suspects it's either a wiring problem or a dirty injector.

He's taken it in his shop (which is right next door) a few times to try a few things, but is a really busy guy and doesn't appear to have time right now to change the injector. I've been bugging him virtually daily for two weeks to solve this problem for me. Apparently it's a time consuming job and I sense that he's avoiding it. Today he recommended I try Seafoam to try to clean the injector, if indeed the injector is the cause of this problem.

Been reading about Seafoam on the web, and the general consensus is that it helps with misfires. Though some people have had negative things to say, like it fucked up their engine. I'm wondering if anybody here has tried Seafoam, and if it helped your engine in any way.

Any help would be hot. Thanks!