GM-GMC: 2002 chevy v6 ses light, chevy v6, auto repair shop

Question
i have a 2002 silverado and the ses light is on and blinks and runs rough. Took
it to the auto repair shop and tech says it needs tune-up. had that done and
didn't fix  it. light still on and still blinks. while checking it again with the
computer, he says that #6 cylinder is misfiring. Is there anything else that could
cause this problem?

Answer
If you have a steady misfire on only #6 cylinder there are only a few things it could be (assuming the tune up was done correctly).  It could be a fuel injector either plugged or not spraying correctly or it could be something mechanical which would prevent the cylinder from creating enough compression to support combustion.  A quick compression test both wet (squirt oil in the cylinder) and dry can check that.  All cylinders should be in the same ball park.  As for an injector, you may need to remove them and test them.
Hope this helps