Car stalls after driving for awhile heavy smoking

I have a 96 Nissan Maxima 3.0 liter v6 with
the vq30de engine. Recently got it running
after replacing a bad alternated with a
frozen pulley. Parts I've replaced this year
are the cam and crankshaft position
sensors, knock sensor and harness,
starter, alternator, battery and connectors,
several vacuum hoses and a few radiator
hoses, air filter, intake manifold gasket,
valve cover gaskets,and the neutral safety
switch. Cel is on but haven't gotten car far
enough to get codes run yet. Was running
fine after new alternator installed but
before I could get to a shop to run the
codes it began stalling repeatedly on the
the highway and smoking heavily (smells
almost like a burning belt or oil) started up
quickly after several stalls but then shut off
completely. Battery still reads 12.3 volts
but wouldnot  crank and headlights
wouldn't come on. Going back today to
see if it cranks while cooled but unsure
why it's smoking suddenly. It comes from
the engine bay and under the car but not
the tailpipe. No squealing from the belts
but smells just like the belt did when it tore
off from the stick pulley. Any ideas on what
I should look at next?