Intermittent starting issues on 99 Jayco Class C Ford E-350

[Banyan]

Has anyone had any intermittent starting issues on the Ford E-350? We have a 99' Jayco 3230K Class C RV (98' E-350). This issue was every couple weeks but has recently become more often, every couple days. Of course it never does it when we visit the mechanic. It typically happens when I haven't started it in a couple days.

It will crank strong but not start. I have replaced the fuel pump but it's still doing it. It's typically first start of the day. Once it starts it will start all day long. The fuel pump is running as I can hear it. If I try it again and again, off and on, it will usually start within 45 minutes. I've tried shaking the wires between the fuel tank and the fuel filter and sometimes that will start it up and sometimes it won't. Occasionally it will start with a stutter then die and then it will typically start pretty soon after that. When it's running it runs really well. It runs a little rough when warming up but not too bad.

Any ideas from anyone?