there are a couple of things.
1. make sure the oil that you you used has a cf-4 or cg--4 this is a anti-foaming agent VERY IMPORTANT FOR THE INGECTORS and the oil is up, when it gets to low it will start to cut out.
2. fuel filter is clean and the heater inside the fuel bowl is okay
3. also make sure the wiring to the heads are okay, there are times they will unplug inside the valve cover which i would get a tech. to do.
4. the crank shaft sensor can cause these problems, they are easy to change and the price of them dropped from $320 to $100. | 
