'91 Johnson 70 HP Starting Trouble

[Trackerman]

I have a '91 Johnson 70HP VRO motor. It was on a boat that had been only sparsely used once or twice for the last year. When I got it in March, I changed the water pump and impeller, serviced the lower unit and it ran fine -- although only a little rough at idle. Last week I got on the boat and couldn't start it. Waited a day and it started only after winding the starter for about 15 minutes. No response at all and then a few pops before it finally started. Had trouble keeping it running while cold but it ran fine after it warm. Starts on a turn thereafter. Will go from idle to 5000 RPM with no problems and I took it for a long run hoping I would burn the problem away. The next day it was the same thing. I had a heck or a time starting it.

The motor was getting fuel. After it wouldn't start I removed the plugs and cleaned them as I think It was flooded the first time. It has an on-board fuel tank; I pumped the bulb and it would get firm and then lose firmness which I don't think is right.

Can you help with my problems?