hello again!, my 1980 240dl is running rough

on the highway at high rpms, if i let off the gas it backfires violently.

my idle screw is turned all the way in! and it will idle roughly for 10 seconds then sputter out,
it will not restart even with the pedal to the floor,

i have to wait a minute or two, then crank it with the pedal to the floor for a good 30 seconds and it fires up in a cloud of smoke!

while driving the engine misses allot and surges, its fine at high rpms

i put new plugs and a new air filter in it,
new oil and oil filter too

i disconnected the air filter hose onto my carb, and now the idle is up higher but the engine is rocking back and forth and its not running on all cylinders until the rpm is above 3k

the slide on the carb looks wet and almost oily,
all the hoses are connected and in good shape, they are not split or leaking,

thanks for any help i can get!

 

Carburetor needs cleaning! Youtube has some How to do videos. Check the
membrane and needle inside and see if its fine.

 

ok so you think a carb rebuild will help?
anything i should look for before i tear it appart? pvc valve? bleed hole?
choke linkage? everything moves smoothly and appears to work