Problem with 92 Excel not fireing on all 4 cylinders

Hi, I have had a 92 excel for several years now, and it has been totally trouble free untill today.
I noticed it running very rough, and have determined that it has
suddenly stopped fireing on the leftmost two cyclinders.
I checked the plugs, and found them to be clean and dry with no fouling evident... Just to be safe, i replaced all 4 spark plugs, roter, cap and ignition leads.
A compression test reveals that compression is normal in all 4 cylinders
What are the types of things that can cause this, and what else can i check without pulling the motor apart ?
Could it be a problem with the EFI ?
regards, Michael
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Could be an EFI issue. Did you verify no spark, or do you just know you have a miss?
Possible the wires could be switched? Firing order is 1-3-4-2.
Possible clogged injectors.
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