Just bought an '86 Cabriolet. 350K Kms. previous owner let it sit for maybe 18 months with fuel in the tank. I put in about 30 litres of 87 octane. Engine runs happily until there's any sort of load other than flat ground. Then it misses and loses power. A sample of the fuel was stinky. Have changed spark plugs, and wires. the fuel distributor has had the sliding valve cleaned. Will remove most of the gasoline and put in some injector cleaner, but I have my suspicions about the fuel distributor system.