I bought a 2006 Komatsu FG25T-16. It has been sitting for several months. It has an LP K21 engine. After the forklift sets for a few minutes with the fuel on, it starts right up, runs great for 10 seconds thens starts to run rough like it is lacking fuel or over fueling. If you start it right back up it will start rough and run rough. Let it set for a few minutes, starts right up again smooth then goes rough. The check engine light is on all the time while this is going on. It seems to me like the fuel builds pressure while it is setting then as it uses it,'it can't keep up with demand. If you work the throttle a bit you can finally get it to run semi smooth at higher RPMs but it still isn't right. What could be causing this? Thanks for any and all help. I am 200 miles from a dealer