It very well could be a matter of driving. It definitely is a different feeling kart and takes some getting used to all the positive front end feel it has.
You’re going the right way; taking front width out and adding rear width.
What front bar? The blade? If so, is it flat (horizontal)?
The OTK kart has two sets of wheels; MXC and MXP. MXC are used by the majority of drivers at a regional/national level because they remove grip from the tire and keep the tire cooler over a run, resulting in a more consistent feel. MXPs are the stock wheels which are used in low grip situations because they do the opposite.
The kart shouldn’t really hop badly on YLC and with all that grip removed.
What are the actual front and rear track widths at this point?