check for vacume leaks first. then check fuel pressure. im betting the fuel pulsater has a hole in it. your inside lights probably have nothing to do with this problem. or it could be your idle air control solonoid is bad. is the check engine light on?
i hope rootpoot never works for me he is wrong on most accounts. sounds like its not in park or the key tumbler has failed. tumbler failure is common on gms. heck i just did a gm truck with the same problem last week. and it was a 2004 go figure
some of the early vw vans if in good shape can go as high as 100 k. parts for these campers are almost obsolete. but you can still find aftermarket stuff. my recomendation is to get online and look it up
all engines gain heat when you first shut them off its called heat soak. when you start it the pump flows and immediately it cools off. as far as the smell goes i bet you have a very small leak somewhere. waterpump?, radiator. heater hose quick release nipple? i bet it is evaporating before it...
maybe its not the additive? maybe fuel pump went out or something, heck it could be more than a hundred reasons why it wont start. i would check it out rel good before you go to the trouble of getting rid of all that fuel. or you can just mail it to me my hot rod will burn almost anything.