Weird issue..
I kept getting a check eng light, only when starting my cold eng.After a minute or two the light would go out.While the light was on though.The MC solenoid would NOT cycle.It was bottomed out(paddle) like it was grounded.I could tell this by looking down the vent holes next to the IAB screw.The paddle was always at the bottom of its travel.

After the 1-2 minutes during warm up the MC would resume cycling & the light would go out.Happened several times til the MC would no longer cycle at all(eng would'nt run either).Everytime i check the trouble codes, it was always code 23(check MC connections @ solenoid/ECM, check wireing).This is all the manual recommended checking.

Anyway, turned out to be a bad EGR solenoid, but i never got a check eng light for this.Why?
When i replaced the solenoid with a good one the problem went away.How?

I cant see how the EGR solenoid would cause this.Is there something else i should look into.

 

The ECM operates those items by providing a ground, so if the EGR solenoid was somehow preventing grounding of the MCS?

Doesn't make sense, but I don't have the diagrams in front of me, either.

 

Seemed to the EGR solenoid was permanently grounded & somehow grounding(or shorting) the MC in the down position.Never got any other trouble codes though.Spare EGR solenoid seems ok, but the EGR valve has vacuum 100% of the time now.Thought it only received vacuum on deceleration?Or is that under acceleration!

What are the chances the ECM itself is bad?Car runs fine.