You should be able to suck the fuel out via the filler, its possable on a mondial. If you are going to use some form of injector cleaner in the replacement fuel, be sure to put the bottle full( about 250 cc size here) in the tank, but only put a gallon or 2 of fuel, so you get a strong mix. No point in filling up the tank if you have such big problems. The Honda fireblade i had played up every year after sitting for the winter, but i used to get away with topping up the tank and it would clear itself
Well, one gauge in an F1 car. Unless of course a guy were to ditch the clock, install a temp sensor in the sump tank and plop an oil temp gauge where the clock was
During the major service, it would be wise to have the throttle bodies synchronized and the stops adjusted. They may correct the stumble you are describing.
So I have been re-united with the car this afternoon and: (a) it does have the O2 sensors plugged in into the straight pipe setup after the headers; (b) there are currently no stored codes. Since this car is an OBD1 car with an Euro ECU I did make a harness pushbutton to connect to the test port and try to see the stored codes one bank at a time - nothing.
From my previous post on this car ~4 years ago: http://www.ferrarichat.com/forum/142410806-post5.html All I ever had (code-wise) on it was the 4121 Catalyzer temp ECU code since the thermocouples were not connected. Since connecting a dummy thermocouple on each side and providing some input to the cat ECU all has been fine.