newbie.. and question

Hello all. I just found this site and signed up today. I'm from Biloxi Mississippi. My grandmother gave me my grandfathers 1991 bass tracker. It has a Johnson 25 HP engine. It had been sitting up for about 2 years. I cleaned the fuel tank and added new fuel. Mixed with correct oil ratio. I changed the spark plugs and it cranked right up. I took it out and it ran great.
About a week later I took it out again, and here is where my problem started. Once in the water she cranked up fine. It ran about a minute and it died. I tried to crank it back up. Every time I would do so, it would run about 5-10 seconds and then it would die. It did this several times (About 20) until I realized it was time to take it back home.
When I got home I hooked up the water and wanted to do some trouble shooting. Surprisingly the motor cranked right up and ran great.
After inspecting the outside I noticed the screen intake covers on the bottom of the motor was broken and need to be replaced. I intend to replace them, but didn't think that could be the problem. I have bought a carb kit and will be rebuilding the carb.
Is there anything else that could have caused this?
Thanks
Shanne

Hell Shanne, First get a Johnson service manual this site offers the OEM manual (mine was a copy but it's great), this will help trouble-shooting and provide you with the knowlage to manitance and service your motor.

1) I would first check the fuel system which includes all hoses, fitting, fill hose/vent hoses. Both under the cowling and from the motor to the tank. As u may just be running out of gas.

2) You need not only to change the raw water intake screens but the water pump as well, also service the lower unit, flush it out and fill with fresh oil.

are you sure the kill switch laynard cover is properly installed (some of the first design were prone to deteration) the second design is bullet proof. Other things to check, when you had it back at the house did you need to pump up the primer bulb again (was it soft or firm)
I would check the o'rings in the fuel connectors for deteration and replace the primer bulb or just purchase a whole fuel line, with this new formula fuel the fuel systems have a high failure rate. Good Luck I will check back.