Rough idle then stalls WM

[Caprice2010]

Hi all.
New here my 2010 caprice suddenly went to limp mode really rough idle then dies. Came up with a map sensor code. I replaced the map with genuine as well as all the plugs and a sus coil pack cylinder 3.
Cleared codes with scan tool still no better. P0106 Intermittent comes up.
Have now disconnected the battery for a few hours to reset all emu's.
So is the next step a compression test or am I missing something.
No clang or clutter from motor just rough idle as if running on a few cylinder. I should mention she's done 500,000ks but reg serviced every 10k.
Replaced lifters about 200,00ks ago AFM.
Thanks Eric

 

[lmoengnr]

Hi all.
New here my 2010 caprice suddenly went to limp mode really rough idle then dies. Came up with a map sensor code. I replaced the map with genuine as well as all the plugs and a sus coil pack cylinder 3.
Cleared codes with scan tool still no better. P0106 Intermittent comes up.
Have now disconnected the battery for a few hours to reset all emu's.
So is the next step a compression test or am I missing something.
No clang or clutter from motor just rough idle as if running on a few cylinder. I should mention she's done 500,000ks but reg serviced every 10k.
Replaced lifters about 200,00ks ago AFM.
Thanks Eric

Checked for broken valve springs?

 

[Caprice2010]

Update on my WM
Did a compression test. Cylinder 1, 240
Cylinder 2, 220 Cylinder 3, 0 Cylinder 4, 180 Cylinder 5, 240 Cylinder 6, 200 Cylinder 7, 230 Cylinder 8, 230.
So I guess valve covers off next to see what is not moving, bent or broken lol.
Or I could sell it cheap..

 

[Caprice2010]

So, pulled the valve cover off and broken valve spring cylinder 3.
Held the valve up with pliers redid compression test and got a reading of 240. I think I may have got lucky.
Thanks for all on here for the advice.
Cheers Eric