456M CEL and SDL

Had my 2001 456M GTA serviced earlier in the year for fluid changes, new accumulators, and ride height/alignment adjustment. My daughter came to town from Oregon and hadn't ridden in the car so we took it out for a short trip. Hadn't started the poor car for about two months and seemed to start fine but upon leaving the driveway it seemed low on power, I assumed it was cold and kept driving for a bit but when we came to a hill the car could barely climb it and was loud and the gearbox acting funny. At that time I noticed the CEL and SDL.

Anyway, got home and after reading about it on FerrariChat, it seemed the car was only running on one cylinder bank. I noticed the right side exhaust was cold. I swapped the exhaust ECU's and cleaned the connections hoping to transfer the problem to the left side but nothing changed, right side exhaust still cold. Also cleaned the right side MAF connection.

Went to the Auto Parts and purchased an OBDII scan tool. Came up with the following:
1. PO300 - Random Multiple Misfire Detected
2. PO305 - Cylinder 5 Misfire Detected
3. PO306 - Cylinder 6 Misfire Detected

Just spent a lot of money on the service which was over 100 miles away. Hate to have it towed if its a simple fix (nothing is simple it seems). Any ideas? Spark plugs? Bad plug wire connection? Coils?

I haven't had a single CEL with the car until now, I hope its not the old gas. Last filled about a year ago plus added some Lucas conditioner to lessen the effects of ethanol in the fuel.
Any suggestions truly appreciated!

 

Question: Does disconnecting the battery for half hour clear the fault codes/SDL or should this be done with the OBDII code reader? I have done the reset procedure after battery disconnect but the codes still display on the code reader.

 

Thanks Alex!
I cleared codes with OBDII this morning and tried again but no success. I am afraid the rubber pump housings are probably shot and contaminated the filters, tank, etc and should get that fixed along with everything else you mentioned above as preventative maintenance. Should I check fuel pump relays? And why are there four relays? Maybe by luck a relay is toast but a long shot.

 

I swapped the right fuel pump and injection relay with the left side which was running.
Started the car and the banks have switched, left bank not running now and right side is.
Success!!!!
I ordered two Bosch replacement relays #0 332 019 151 which will be here next Tuesday.
I will report back when all 12 cylinders are running again!

 

Replaced both fuel pump relays and the V12 sings again!
Note in photo the new relays are brown instead of black.
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