I have a Craftsman riding mower with Honda16.5hp engine(GXV530). The Mower started spitting and sputtering, so I changed plugs, air filter, checked valves, cleaned carb. Put everything back together. Left air filter out to start, and everything seemed fine. Got ready to mow, put (new)air filter in and mower started doing the same thing again. So today I started cutting grass and it just spit and sputtered. I pulled the (new) air filter and it ran like new. So confused. I had some experienced mower repair people talking me through this, but I'm stuck. I can cut with filter out, but I know that is not advisable. Wasn't dusty today. Would appreciate any input.