Hi @metal_heart I too bought a used GP 90hp 2010 recently. I had the same problem with the MID showing 'Airbag failure' and 'ABS not available'. I too tested the battery which was good. Yet it turned out that the battery was the culprit and after replacement of battery I no longer get these messages. Please test with a new battery installed and see if the messages are still coming when you crank the engine. That way you can clear the air. Coincidentally I too had issues with pick up/hesitation when I bought it. I cleaned my MAF sensor with Isopropyl alcohol 90%. I used a plastic bag, by filling it with IPA and put the MAF in it, closed the bag with a rubber band and left it overnight. In the morning I shook the bag thoroughly for a while and allowed the sensor to dry for an hour in shade after draining the IPA and taking it out of the bag. It worked. I believe you are yet to have a look at your intake Manifold, MAP sensor and EGR. Hope giving a good clean to these, hopefully would solve the pick up issues, as it did for me. Also have the oil separator check for any blockage. Blockage in oil separator means breathing problems to crankcase due to increasing pressure, on account of blowby gasses. In my case the oil separator was completely blocked with oily gunk and I replaced it for the better.