Its possible, as old as these engines are, (15+) I would buy a inline spark tester, like one you would use on a Briggs engine, this is one like i have. you hook it up to the plug wire, and clip it to ground, or on the spark plug, if you've got a orange, yellow spark, coil is weak, if its blue or white, thats great! another thing could be a faulty spark plug, sometimes under higher pressure (such as revving the engine) the spark wont jump the gap, the plug i use on the 550 is NGK i BPR5ES. i would also be sure the plug gap is correct, should be 0.028-0.030, you might also try gapping it slight smaller than spec, if your coils weak it wont have enough oomf to jump the gap over high pressure. EDIT: one thing i would do, is when it starts to bog while revving, choke the engine, about 1/4 of the way, then half choke, then about 3/4 of fully choked. if it runs better while being choked you have a lean mixture of air and fuel. or more air, not much fuel.