Hi Guys, got a performance exhaust and cone filter today for a 156FMI (ohc) engine, received two 105 jets, opened the carb up and replace main jet 94.5 with the 105. Got my colortune out, tweaked the mixture, I have a blue flame on idle or a set rpm, on acceleration flame color is yellow, every seems to work okay. But as soon as I take it out onto the road, at low rpm (<4000) it works fine anything mid or high end it struggles and stutters.

Any ideas, advice or help?