It starts on the first pull, then there is a subtle sense of roughness. No noticable smoke. Probably not full idle RPM. If I engage the blade on the driveway, it may or not keep running but will sputter and struggle. It definitely won’t handle the load of mowing a normal height lawn until after the warmup period. Toward the end of the warmup it becomes obvious as the engine starts to sound smoother.What does it do during that 5 minute warmup? Blowing any smoke? Runs slow? Slowly comes up to speed? Any surging? Just suddenly jumps to full speed? Remember we aren’t standing next to you, with a strong drink you provided, to see what you are seeing. Can you paint us a better picture of what is going on.