70EL76D issue

[jvmvjv2]

Hello everyone. I have a couple of questions that hopefully someone might be able to guide me. I purchased this motor and I found out from the owner that it was in storage for about 7 years. (First thing I did was buy the manual for it) I mounted it on a 1966 Winner 16ft fiberglass boat and I'm going to use it for fishing. Basically its my first boat. This is what I have done to it so far: Before all of this, I verified the motor started.
1. Replace water pump
2. Replace fuel pump
3. Replace thermostat
4. Replace Plugs
5. Check cylinder compression #1-135psi #2-140psi #3-138psi
6. Replace propellar shaft seals (because it started leaking after initial start)
7. Replace lower unit gear oil
8. Replace all fuel hoses
9. Water intake screen
Well thats pretty much what I've done. Now I took it out on the Hudson River in NJ. At first it ran great. I had good pick up and the power was there. Like I said before I'm a first time boat owner so ofcourse I messed up and ran out of gas, but I had a second 6 gallon tank just incase that happened. Here is where the problem started. I switched tanks and primed the buld untill it was rock hard. I tried starting the motor but It took a while for it to start I would say about a good 10 minutes of cranking allowing the starter to rest. After I got it started it just wasn't running right. It would sputter while in neutral and when I would shift into drive it would shut off. This went on for about half hour. Finally it would stay running while in drive but had very little power. I had it open all full thottle and it barely moved. While driving back to the launching ramp it would occasionly, out of no where while, at full throttle just accelerate and work great then it would just bogg down again. After I got home I double checked all my work and it all seemed fine. I though their might of been a problem with the spare gas tank I had so I refilled the first gas tank and took it out again, but it was doing the same thing. So my question is why did it take so long to start and stay running after I ran out of fuel and why is the motor running great one moment the it runs horrible the next and it goes back to great again?
Any input would be appriciated.

[boats.net]

Could be an ignition problem or trash could have clogged your carburetors. First start with ignition, when the motor is acting up check all the cylinders for spark. If there is spark then should be a fuel problem, you may have sucked up some trash from the bottom of the tank.

[jvmvjv2]

Please help.

I rebuilt the 3 carbs and today was the first nice day to take it out. So.... I took it out and it ran great on the way out. I ran it for about 30 minutes then I shut it down and did a little fishing. After about 20 minutes I decided to start it and move to another location AND hear we go again... It started doing it again. It would crank and start but it would run rough. I would allow it to clear then shift it into drive and it would shut down. That went on for about an hour. I checked the spark and all 3 cylinders had good spark. I checked the water intake screen and it was clear. Then finally it stayed on and it ran like a champ again. So once again I shut it down to do some fishing and when I tried to turn it on again it did it again. Im at my wits end. I dont know what else to look at. One thing I did notice is the priming bulb would not get hard.

[boats.net]

Unfortunately I am with you, very stumped.

[greengizmo]

JVM, try replacing the primer bulb and hose. Is bulb collasaped or needs priming when problem happens? Are you flooding carbs trying to start it? Sounds fuel related to me. Bulb usally stays hard once primed for the days outing.New fuel filter/water separator? Take a fuel sample?Is the fuel system free from kinks and loose fittings? Just some things to try.Stick to basics first before going deep into things.