96 mariner 175 efi will not run cold temps

[Elishaman]

1996 mariner efi hard to keep running when first starting at temperatures below about 37 degrees. Once you get it to keep running for 3-5 minutes it is fine. Starts and idles perfect at temps above about 40 degrees. I have checked the air temp sensor and engine temp sensor. I replaced the fuel filter. Fuel pressure is about 39psi which is above specs by 3 psi so I can't imagine that is the problem. Have owned since new and always used pure has or added stabil if pure gas not available. Always kept in my heated basement.