787 rfi surging?

[Bearit]

Hi guys
I bought a 2004 3d for my kids to use at the cabin so they would not ask to use my rxp,they used it last year and put 15 hrs on it,at the 10 hour mark I took it in to get serviced and told the guys to check the opas out as it would flash off and on after about 2 minutes of driving and the opas did not seem to be working,they checked it out and said there was no faults to be found.

Now on the first run of the year it seems to be surging like one cylinder is kicking in and out at all throttal positions except at idle when it is only on the one cylinder,and the opas light still comes up,I took it back and they said the computer could not find any faults,so I brought the mechanic to the lake and showed him the surging and he hooks up the buds system and still canot find a thing.I have added fresh fuel and changed the plugs,and the mechanic played with the throttal position sensor but it still is happening.

It has been a month since I brought it in and I had to phone Brp and complain about the service I was getting,so now the mechanic has ordered a new ecu,and a computer, is there anything else I could tell him to check as this has gotten to be a real payne in the ***.
Thanks Steve

[RiverRat19405]

had same problem surging puled carbs an took out 2 lil cone shaped fuel filters one was clogged shut cleaned both runs great now no surging

[winterstick]

no carbs on rfi
could be what ever makes it idle on one cylinder is not working correctly and doing it at higher revs.
did the mechanic check the tps position?