noob needs help with mileage - only 10 MPG!

Why "ask about" valve adjustment instead of checking and doing valve adjustment? If you are at the mercy of a mechanic, it's a good chance your wallet will drain dry before your car's running right. There are lots of slant-6ers in the Portland area; if you post on slantsix.org someone will likely speak up to help you. Meanwhile, get the three books in this thread and follow the advice in post #29 of this present thread.