Crazy talk. Pull the pan and clean out the debris. Replace any bent valves (not sure what "one half of the engine shutting down" means") and the tensioner. If your mechanic is afraid of valves, I have a head with the cam chain adjuster in it for sale. $250 plus shipping.
Consider doing a timing belt service at the same time if the service is due soon.
If you decide to bail out and sell the car as is, I'm interested. Been looking at 4.2's lately.
Growing old is mandatory; growing up is optional.
2005 A6 Sedan Q 3.2 (wife's whip)
2003 S8 (Q Ship)
2000 A4 Avant Q 2.8 (daily driver)
1999 BMW M Coupe (clownshoe)
1980 VW Scirocco (mid-life crisis car)
1983 Mazda RX-7 (revolutionary sports car)
1999 Mazda Miata SSB (track beotch, no plate)
2003 GMC Yukon Denali XL (the anti-earth)
2004 Dodge Dakota (hey, at least it's stick and 4x4)