Pull the air filter off, Watch the linkage operate the throttle slide. You'll see what's going on. ALWAYS adjust the linkage mechanically before turning the trim knob. Set the trim knob back down to the point so the throttle slide stops at neutral, and at full brakes.
Then check that the servo/throttle linkage opens the slide just a tad shy of all the way open. Lean the LSN in 1/8th of a turn in. Get the engine hot before you start it, use a hair dryer or a heat gun. Idle stability will improve with the engine warm. Fuel flow is controllled by the LSN from idle to 1/4 throttle, after 1/4 throttle the HSN is what you adjust. If it floods out too easily in either range, lean the appropiate needle. When you lean the LSN to the point it needs to be at, you will have to turn the idle speed down with the screw on the carb. Readjust the linkage at idle to compensate.
I think you need to do some research on here before you go any further. Read the manual front to back until you are 100% familiar with it. There is a couple of stickies at the tops of the different forums, they are for the new people.
Welcome to the forum BTW! I hope that helps.
You can also ggogle "RC Nitro Engine tuning" and come up with a ton of information.
Maybe you'll luck up and find someone near you with experience to help you out. I had to learn the hard way myself. Solo over 10 years ago, I feel your pain. We all did at one point. I'm STILL learning more and more about setting up r/c's properly everyday!
