Hello Simpleplanes community.

I'm trying to build a new aircraft (a crop duster), but I'm having issues with uncontrolled yawing on takeoff and landing. But my main issues are the speed. The aircraft has a really bad climb rate, a slow speed no matter how much I increase the power, and it's hard to slow down and actually stop and stay stopped after landing.

Could somebody have a look at the AIRCRAFT and mabye fix it or give me tips on how to fix it?