Couple of issues with an S13 - brakes, gas, etc.

[SupaDoopa]

I picked up a 91 S13 hatch with a S14 KA-T with a T28. There are a couple issues. The car originally came with Super HICAS. It was removed from the subframe to pipe. The cars ABS also rarely works as is the light is on. The problem is when I hit the brake pedal, it goes all the way to the bottom and slowly slows the car down. I checked fluids and can't seem to figure it out I will be checking the lines to make sure they aren't leaking, but if someone has an idea, that'd be good too.

Also, if I'm driving and then hit it in neutral to come to a stop, when the car is warmed up, it will stall out. The car idles at 700-800 when first started. I would like to think it has something to do with the IACV but I'm not sure if it's the tune. It has E-Manage but driving, it seems fine - it's when I stop that it gives me an issue.

They seem like small issues and the obvious cures I will be looking at but would like second thoughts in case what I am looking at all seems clear.

Thanks for the help, guys.