twin 250 ox66 fuel injected

[Dr1532]

I installed twin 01 250hp, when i bought these motors , did head gaskets , pumps, installed the new 10 micron filter on the side of the blocks , new vst filters, put new 10 micron filters in line, tank has a dual pickup, motors ran flawlesly until 2 days ago as when i went to take off the starboard engine started to surge it would drop right down to a bare min rpm and go back up , down and up .it came out of it after a few mins, when i got home I pulled the vst tank and looked at the filter ,it was spotless so i put it back together, took the boat out toninght, motors ran fine as there is a mile long 5 mph, and when i went to take off it did the same thing, now both motors are doing it, I pulled off one of hoses to the pickup incase I had a vent issue , no change, blow back into the tanks pickup lines seemed clear, drained out one of the 10 micron filters no junk, the only thing these motors have that are link together is the battery switch. also tried primming the primmer ball , did not help , a tough one for sure , aswell an agrevating on to boot

[TCSavage]

O2 sensors??

[Tucker]

02 sensors would be my guess too. The only thing casting doubt is why did the 2nd motor start doing the same thing? Search 02 sensors and find that procedure for cleaning.