Slant six help needed!

I have a 225 ci slant six. In the morning I pump the gas pedal 5 times, start the car, idles rough, idle smooths out after a couple mins, and let the car idle for about 10 mins. I step on the gas a few times (still in park) and the car cuts off. I start it again, then it's fine for me to drive to work. When I don't let it warm up long enough the car cuts off in the middle of the street. Today it cut off on me 5 times on the street. Also a couple times the car refused to start in the middle of the day, all warmed up already driven 30 miles. Is it normal for slant sixes to need a lot of time to warm up? How can I fix this problem? THANK YOU!