Today my Red Max was running pretty poorly, again. This has happened several times before and with other Red Max's as well. It runs like the choke is partly on or something. Maybe gets up to about 1/2 to 3/4 rpm's at most. Spark plug "looks" good. Air filter is clean as a pin but I pulled it off and ran it just in case; no difference. Pulled the fuel filter off and ran it; no difference. No kinks in the fuel line or anything I can tell. What's even more curious is probably Monday, it will run like a champ. I've had 7000's and 8000's do this from time to time. The 4000's have never been a problem in the past. Anybody got any ideas? Thanks.