96 Tahoe Intake Leak & Bank 1 #2 O2 Sensor

[boyscout]

Hi everyone I'm new to this forum but not to auto forums. First time I've needed one for my Chevy.

I found this winter (when the heater quit blowing hot) that I had a coolant leak. After a pressure check I found a leak at the front of the lower intake manifold. Few searches on the forum and this seems to be a common issue. Not looking forward to taking the top end off. Last summer did a head gasket job on my Ford so I'm not in over my head. Figure I'll do the gaskets on both valve covers while I'm in there.

Towing the boat a few weeks ago I threw a #5 misfire and bank 1 #2 O2 sensor MIL. I'm going to start with the CAT. The muffler shop that did the custom exhaust on my CJ7 test CAT by reading temperature in-front and behind CAT. Tonight I'll break out the temp gun and see what I read. Not sure what level of temp variance would signal a clogged CAT.

I also noticed the idle has a slight rise and fall. Could be a vacuum leak in the intake, clogged CAT, or bad PCV valve. I haven't attempted to smoke it looking for a vacuum leak, but I can't find any obvious leaks.

 

[boyscout]

I know I didn't post any real questions, but I am fishing for advise. The most I've done to the Tahoe is a fuel pump replacement and pulled tranny for a rebuild. Shop rebuilt it I just did the heavy lifting.

 

[lesterl]

#5 missfire could be ignition, compression, or fuel. Vortec is notorious for bad injector poppets.... Pull the spark plug and see what it looks like.