Been having a few problems with my 1985 998 Austin Mayfair. Was hearing some really bad pinking in the engine the other day so i decided to check the ignition timing using a timing light. Found it was way too far advanced. So I adjusted it back so it is now at 8-10 degrees at 1500rpm. However, I seem to be having some really bad power loss issues and also backfire through the carb when out driving and accelerating hard. For some reason on a start up I did it was sounding really lumpy as if it wasn't running on all cylinders. This baffled me so went in for a cuppa and came back to it. Turned the engine on and it seemed to just vanished and hasn't returned. I've checked the dashpot oil. I even drained it and refilled it. After a good 15 minutes of running, I checked the spark plugs which seemed really black with soot. Any help would be very much appreciated.