1989 Chevy S-10 missing

1989 CHEVROLET S-10
106,295 MILES • 4 CYL • 2WD • MANUAL
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OUTSIDERDGN
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  • 1 POST
my truck will start missing going up any grade of hill
but sometimes it wont and nothing i do will change the problem.
i have changed the erg valve, a complete tune up, coil, computer, oxygen sencer, throttle postion sencer, map sencer, temp sencer, rebuilt the throttle body, and it still starts missing when i drive up hill after i top the hill it will stop missing again.
Apr 15, 2009 at 6:17 PM
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RASMATAZ
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  • 75,992 POSTS
Test for excessive backpressure on the exhaust system to rule out a clogged catalytic converter

Other probable causes:

Dirty fuel injectors (cleaning the injectors often fixes this).
Bad MAP (manifold absolute pressure) sensor
Bad TPS (throttle position) sensor
Bad or dirty MAF (mass airflow) sensor
Low fuel pressure (leaky fuel pressure regulator or weak fuel pump)
Vacuum leaks (intake manifold, vacuum hoses, throttle body, EGR valve)
Bad gasoline (fuel contaminated with water or too much alcohol)

Sometimes, what feels like a hesitation is actually ignition misfire rather than lean misfire. The causes of ignition misfire may include:

Dirty or worn spark plugs
Bad plug wires
Weak ignition coil
Wet plug wires
Apr 15, 2009 at 6:21 PM