My 1994 suzuki swift, keeps vibrating as if it is going to shut off when i stop. What causes that?

The engine is misfiring. NO ENGINE size even stated,!
runs ok fast?, not stated, but implied?
note that low rpm hot is wrong. 800 is normal.
the conundrum is , misfire causes low rpm
and low rpm also make the engine shake...
both do...
misfire has over 50 causes!. guessing is for kids, right, rich kids.... very rich,,,,$$$$

we do tests, that use Physics in to play and are called gauges and meters. to find the truth, 1 of 5 ways.
so its your choice guess 50 times, or do 5 tests.
what is it , gue$$ or test?

bad engine mounts don't cause stalls. sorry !
here is the 5 way list ,posted vast times. and is in the ASE books,
if you care to read how to fix cars, ASE classes do wonders..

each step has a simple test....(or simple inspections)
1: lost 12vdc to the EFI system (stalls or misfire>)check voltage.
2: lost compression to 1 or all cylinders, 45 cases) ask for tests.
3: lost spark, #1 cause is never doing 60kmile tuneups in a decade.
3b spark timing way off, do to cam drive slip. belt or chain
4: bad fueling rates (lean misfire and bogging or rich flooding misfiring.
5: EGR stuck open, or CAT melted (not cat if runs fast ok)

there is a test for each of the laws of physics above.
the tools are like $20.
so do you want to gue$$, or test.

ok , now my useless guess.
never had a 60k mile tuneup in a decade. (full)
like most. and all misfire....all.

even a loose ignition fuse can cause misfire.
#1 above. covers that.

a sticking closed ISC would be #4
why is that? because lack of air causes gross rich conditions, or at the least just the air alone starves the engine, and the ECU does not mix accurately at low air flows. making this worse. we clean the EGR and ISC at the 60k mark, just like the FSM book states.
called doing the full service.

Sticking IAC or throttle blade, bad tune u parts, hanging EGR, bad engine mounts.