Can you check the spark on all four cylinders and report back? Don't get bitten!

I'm just guessing, but since you just replaced the fuel line, I would start there and double check all those fuel connections. You might be suckin' air in somewhere and the motor is starving for gas. Also, check that all four carb butterflies are funtioning as you move the throttle from neutral to wide open (engine off).

Your Craftsman multimeter will probably accept a DVA adapter ($62.00) and you can become a master on your electical system in one afternoon.
Find CDI/Rapair online and search for "DVA Adapter". This allows your standard multimeter to read really fast pulses of DC and AC voltage and holds the reading on your meter so you can see it (before it disappears).