[michaelovitch]

when you press the pedal your idle speed circuit is not working anymore.
when you release it it's working. (and your car die)

when you press the pedal your pump suck more fuel too.
at idle only a little.

that mean your problem is on your idle speed circuit or your fuel supplying.

seen the problem came suddenly i would say your pump is full of crap seen that you run on wasted oil.

like it was said flush your pump and use diesel fuel to start it.

you pump is maybe trying to suck like mad at idle to have fuel but can't because of a restriction.
if it works when you add fuel pressure and rev it up that mean you counter the restriction.

blow your fuel lines with compressed air (i did it with my mouth it's enough) in reverse direction.


change your filter.