Greetings,

If you want to eliminate the possibility of bad fuel, you also need to drain
the fuel/water seperator and install a new fuel filter.  Just putting in
more fuel won't eliminate the problem.  In fact, if you picked up a very
large bunch of trash in your last fill up you may even want to get the tank
pumped out as well.  You could draw some out of the tank and take a look at
it to see if it has a load of dirt or algea in it.

Is your service engine soon light on?  If it is (or even if not) you should
have your computer hooked up to a scan tool and see what trouble codes are
stored.

Let us know what happens.

Cheers - Jonathan

I just had the same problem w/ a customers 02 GMC 3500 van.  To make a
long story short... The right side catalytic converter broke up and
clogged the muffler.  Hook up a scan tool and check for "cylinder
misfire", if you find that 1/2 of the engine is misfiring disconnect the
exhaust pipe at the manifold and start it.  If it runs ok then remove
that pipe and check for cat guts in the muffler.