1988 Gmc Jimmy Hello 88 4x4 4 3l Just Starting Buck Seems Lose Power Reach 45

1988 GMC JIMMY
68,000 MILES
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AUTOHOUND
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Hello my 88 jimmy 4x4 4.3L just starting to buck and seems to lose power as I reach 45 -50 mph i slow down start to pick up then does the same friend at my local shop hooked it up came up with code 42 timing /spark issue could this be the ICM starting to go bad? hope you can help!! ED
not what I need a my truck acting up good old Sandy wrecked most of what I have already thank god for good friends!!
Nov 7, 2012 at 3:43 PM
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HMAC300
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see the two pic i've enclosed. first one is how to check it second one is schematic so print off both and try to enlarge. disregard the top above yes as it means to set the code .just follow it to diagnose it.
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Nov 7, 2012 at 3:53 PM
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