I tuned the car a week ago and had it mistakingly on like 7 degrees advanced timing (or a little more), thankfully nothing bad happened to the engine. The car ran great and was sitting at about 35 KPA at idle.

I've just adjusted the timing(on a fresh base map) to be correct and now the car struggles to get up hills, and it's KPA at idle is 58.

The KPA is the only thing that I noticed a change in (AFR readings are still good).

I've replaced my vacuum line and I am sure that there is no leak (especially since the KPA changes whenever I change the timing.

How do I get the idle kpa to lower and get closer to where it was?

 

Either your ignition timing is incorrect or your cam timing is wrong.

List the steps you used when setting the ignition timing.