I forgot to ask, have you replaced the fuel injectors #4 maybe clogged enough to cause your issues

 

I just picked up some CRC throttle body cleaner. I will get to work cleaning that and checking everything else suggested tomorrow. Thanks for the help

 

Be very careful cleaning the throttle body - do not move the butterfly manually, as one can strip the gears on it, meaning a new throttle body will be needed. So a search for throttle body cleaning for some tips on it.

 

Give this thread a read twistedjay...

https://www.chevyhhr.net/forums/how-...le-body-50000/

 

I was looking for that , and you had it in your computer, thanks Mike!!

 

After cleaning the throttle body (which looked very clean to begin with) I checked my codes again. Still had the cylinder 4 misfire code, along with two codes relating to the MAF sensor. I went ahead and bought a new acdelco sensor and replaced it.

Now when I run a scan I get the cyl4 misfire code, and p0201 and p0203, which are malfunctions on fuel injectors 1 & 3. I am totally stumped at this point and unsure what to do next. Wondering if I may have an ECM problem?

So far I have: replaced plug, coil, and injector on cylinder 4. Also cleaned the throttle body and replaced the MAF sensor. Any ideas would be greatly appreciated.

 

Whilst you did all of this did you disconnect the negative cable at the battery! If not try an ECM lobotomy , and disconnect the battery negative cable for 30 minutes to rest the computers.
During that 30 minutes check all those connections .

 

I did that a few minutes ago. It cleared all the codes except the cylinder 4 misfire. And the service esc/tsc light return with a couple minutes of idling.

 

Educated guess carboned up or burnt valve!

 

Not what I wanted to hear, but I'm afraid you may be right. I'm hoping rislone can work a miracle.