My 80 Malibu V8 305 4 barrel won't stay on unless I'm holding down the gas or I put it in neutral and sometimes both. Earlier today it died on me when I was in traffic but ran fine when I wasn't in stop and go traffic but I pulled over and sprayed carb cleaner in it and it ran fine after that. I also put Berryman B-12 in it 2 hours before this happened just to help out. Can anyone help?