My Echo PB 2400 Blower fires up primed and choked first or second pull, but dies out in a couple of seconds choked or not choked. If I keep priming, choking, starting and unchoking, it runs longer and longer each time until it runs constantly, but only at low throttle. If I gun it, it dies. If I get it running at low throttle for a couple of minutes I can slowly throttle up to a working speed and then it works fine including idle. Once it is warmed up, it starts fine. Is this a fuel system problem or something else? Any ideas?