Audi 80 PM starts after the start…

Hello! Since my beloved Audi has been standing for two weeks it goes down the drain… When it is cold it sometimes starts well, but goes out after 1 minute. If it doesn’t go out it does not take gas, if I step more energeticly on the gas it almost drains, I can only gently increase the speed (if it is not idle). I think it is a bit easier with a warmer engine. Yesterday I changed air filters on suspicion (was quite dense) and the coolant temperate. this morning I tried to start again, then he ran a little longer (5min) with stand gas of about 1900 (slowly decreasing), but then went out again. Do you have some tips what I could check?? LG Sebastian