2001 Mercury Sable - 3.0L Misfire

[alphaauto]

We have a 2001 Mercury Sable LS 3.0 DOHC.. with a idle misfire on #1 and #2....
Installed new coil,checked is working,,,zap.......
Installed new wires and motorcraft plugs...also replaced intake plenium gaskets and egr gaskets....
Misfire goes away or is not felt when raising idle or rev up motor.. Let come down to a idle and then it is noticed..
Any ideas.....Hate to keep taking upper plenium on and off 100 times.....
Possible head or head gasket issue?????

[brianp87]

Why did you replace the parts? Did you check compression on the missing cylinders? Have you checked the fuel system? I need more information to help.

[ricmorin]

What are the fuel trims at idle? Compression test results? Let's determine if it's a lean misfire or mechanical/electrical.

[alphaauto]

OK Customer tried fixing car them self...Had #1 and #2 ,,plus #5 and #6 misfires....
He put new plugs and wires only...Found all these wires crossed....We routed all spark plug wires and pulled all plugs to check air gaps...
Replaced plenium gasket (which) he left the old one on.. Add ripped up old EGR valve gasket.. So we installed new one... Reassembled vehicle and #1 and #2 cylinders missing only at idle #1 is worse...
Watch misfire count on scanner climb 10,,56,,150,,1289 etc..
#2 has stayed in 128...165...198,,,,
REV engine misfire count stops...Idle starts again.

[ricmorin]

So tell us what the fuel trims are at idle, especially on bank 1.

[alphaauto]

Update .. Customer has decided to pull vehicle and not do any further diagnosis or repairs to vehicle...So i can't test the vehicle or give a final answer to what might have been the problem...