P0300 Random misfire on 1998 Chevrolet S10

I change out the ignition coil;fuel filter, wires,PVC,plugs,rotor & cap and air filter,clean thottle body check for vacuumm leaks. the codes was reset after driving for about 20 miles check engine light came back on check code same P0300 Random misfire Answer #1 (0 ratings) Russ, February 11, 2009, 20:08 Can you feel the engine misfire? Any other codes? Which engine is in your S10? Manual or automatic transmission? I can not feel the engine misfire it runs a little rough at idle but very little have 1998 gmc s-10 4.3 v-6 and no other codes shows up

by in Friendswood, TX on February 11, 2009
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2 answers 1 comment
ANSWER by , February 13, 2009
You may have a problem with a worn distributor. With the cap and rotor off check for excess play in the distributor shaft or excess oil residue in the distributor housing. If the distributor checks out ok you may need some help from a shop of a friend with a scan tool so that you can look at engine data when the fault occurs and try to isolate the problem.
COMMENT by , September 17, 2010
A valve seat issue is one possbile case for an engine misfire that you cannot feel.
ANSWER by , September 13, 2010
check for broken header bolts and leaks between headers and engine block.