problems eb falcon series ll ???

[ridebmx14]

hey i bought a eb falcon gli series ll, it was running fine when i bought it. when i was driving back into town run low on tank coughing and spluttering, only just made it home. The next day put 30 litres in axidently put 10 litres of 2 stroke , idiling like **** give it a bit of gas and it would splutter and take a while to respond but sounded fine after that besides it use to blow my air box off backfiring through airbox alot drove around 1 full tank. I replaced fuel filter nothing. Then i checked fuel pump runnig fine plenty of fuel going to injectors. some1 suggested fuel pressure reg. replaced that no good. check compression in all 6 cylinders all good. Then started to run really rich, start her up and foul plugs out in bout 1 minute and stall. replaced leads and spark plugs. Found a leak in vacuum hose from map sensor fixed that Now it wont start it was firing a bit but now i try and it just turns over it doesnt fire. some 1 even suggested the cat convertor took unbolted whole exhaust sytem from header pipes nuthin. please any1 got any ideas im out of ideas and dont wont to spend a heap at the mechanic always fixed my cars myself. but im stumped. Thanks