well, it is an electrical/sensor problem.... sometimes sensors are bad but can stop acting bad for a while, i dont know if that makes sense but when my tps in my car started to go bad... the engine light would be on and my car idled starngly... sometimes it did and sometimes it didnt...
either way, good luck, and i hope your problem stays away for a while.

 

adjust your distributor it probably needs to go back just a tad,i had that problem before. thought it was electical,then thought it was fuel but it was the distributor

 

we already covered that he was throwing a code for the vss...
distributor being off a hair would not throw a code

 

pull the little caps out of the inkectors and spray carb cleaner thru it as well as the injectors