I have an 05 trailblazer ext with the 4.2l inline 6, and a 4l60e transmission.  recently I've been having some issues. Yes it's possible that all the issues are just that separate issues that need to be fixed, it does have 227 thousand miles on the body(and possibly the trans) but I'm thinking the problem is actually my PCM. Here's the issues:

•bad catalytic converter yet I just installed a brand new one

•bad 02 sensor 

•misfire in cylinder 1

•random misfire 

• that random has now focused on cylinder 3

•shifting at higher rpms than normal (3k rpms or more)

•no check engine light comes on the dashboard except at start up with the rest of the dash lights

•internal check engine code with no description and no light

•at top of 2nd gear transmission goes into neutral and will not shift up or down until I come to a complete stop and manually switch from drive to neutral and back to drive

Now I did change the coil pack in cylinder 1 because when I went to switch locations and see if the code changed the bolt broke so in order to get a new bolt I had to purchase a new coil pack. I know you should change all of them but money is tight and my plan is grab a new one each time I get paid and once I have all new ones switch em all out. Oh and I did change the spark plug in the same cylinder cause it was cracked like a "v" when I checked it. When I changed the cat, I had no codes for the sensors until I started having all the other issues, all of which except the cylinder 1 issue came at the same time. 

So I guess my question is am I right about needing a new PCM? I just think it's a bit odd that all of these issues would happen at the same time while the dash gets no check engine light to alert of codes. At first I was thinking my "B" shift solenoid is bad but then I started looking into that PCM, if it's bad it might not send codes and trigger the light, and since it controls when the solenoid is to engage and shift, if it's not working then it can't tell it to shift, it doesn't even shift from 2nd to 1st once the rpms are up high enough. I would appreciate your input very much. I really don't want to spend tons of money on fixing each issue one at a time when it could be something as simple as the computer... although my PCM has been discontinued so it looks like a trip to the junkyard to gamble on pulling a decent one. Problem is these are bolted to the side of the engine cause ya know....Chevy forgot heat is an electrical components worst enemy 😂

Thank you and I apologize for the long message, just wanted you to get a full understanding!