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Q: failed HC idle test on 1995 GMC Yukon

Rookie cbe0621eac06868b3efe0d8d1d3611e23c60d3114864ea2ec19a68cfbd3eebab
Hi..I have a 95 GMC Yukon..failed the low idle portion of the test (NJ) Reading was 726...Standard is 220..Co% reading was .73..standard is 1.20...The truck passed the high idle portion of this test..Just wondering what I can do to bring it down..egr valve was replaced exactly 4 years and about 30,000 miles ago..converter was replaced 2 years ago..however..the repair shop put on smaller exhaust pipe and a generic (small) converter. they did the last emissions test for state inspection, so I dont know for sure if it passed, for all I know they put the wand into another vehicles tail pipe..anyway, just need to know besides a basic tune up what I should do?
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when was the last time you did a tune up with plugs?? common for the plugs to cause high hc.

It is def due for plugs and cap etc..I'm going to do that tomorrow and take it back through..I was just reading that plugged egr holes in the intake will also cause high hc..the test for that is while running push up on the egr valve, if engine stalls there is no clog..if engine stays running there is a clog in the intake. I'm also going to remove the throttle body and clean all around the MAF sensor like zee suggests..there's 185,000 miles on the engine and still runs amazing..lots of oil changes..I will repost tomorrow..thanks
Incorrect cat. converter and restricted exhaust flow could cause this. I assume the air filter is clean.
Dirty or bad MAF sensor could also cause high HC.
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