New Purchase stalls and found oil spray

[fred_e81]

Hello everyone,

Im back with a new purchase. A 1981 GMC Sierra with a 350 and automatic trsnsmission and a propane kit on it. I test drove prior to purchasing and it ran well. On the way home on the freeway, she coasted great. Suddenly I smelled oil or ATF not sure which one. I pulled off the freeway and took the back roads home. While at stop lights she began to stall. I'm going to start with the free stuff, vacum leaks, plugs wires, cap and rotor. Where else should I look? Also, where do you think this oil is coming from? It splattered all over the carb, only the carb. Any ideas. It was dark when I checked it and I took a pic as well.Thanks in advance for any and all help.