If the flex pipe is cracked, will that not set off a code and make the engine light come on? If it does I would not start changing parts until I got that issue corrected. Fix the known issues first and then keep diagnosing. I hate to throw away money.

 

A cracked flex pile will not necessarily throw a code - mine sure didn't. Check out this flex pipe thread - https://www.chevyhhr.net/forums/prob...acement-48707/

That being said, if the flex pipe is cracked it's best to replace it first off. Fix the known broken things first - they may be related.

 

mine set a code , don't recall the code, and the exhaust fumes in the car were awful strong had to keep the windows up and the recirculation switched on for the A/C
and as I recall Donbrew had a code when his flex pipe cracked