1988 3.0L Problems

To Any and All,

Help!!  My poor '88 runs like it's missing a cylinder firing.  It sat for a month without being ran.  When I tried to crank it after a freeze it wouldn't start; seems the fuel pump and lines were froze.  After thawing the thing still wouldn't crank.  I had to drastically advance the timing to get it to start and it runs like it's not firing on all cylinders.  I found a vascuum line off and that helped.  Took it to local Toyota dealer and they say it has a blown head gasket ($1100.00) and may need a new engine (+190K miles) though it ran fine before it sat up.  when I got it back from them it actually ran better and cranks easily yet still runs as though it's not firing prioperly, also the exhaust smells funny, like it's excessively rich.

Can someone please give me some idea about where to start to find the problem.  As much as I hate to say it I don't trust the dealer's diagnosis.  Thanks.