88 turbo 2

so my car came with a hks f-con and the gcc by hks

i had my local mechanic tune my car and it turned out to be a nightmare..

when throttled heavily my car starts to cut out now (was not doing this before the fail tune) and the air fuel ratio drops down or below 10 and begins to cuts out.

My general afr is all over the place as well.

I own a aem wideband. If anyone can help with some general settings on the gcc so i can get an idea, or anything i can do myself to tune it without spending money back at a shop that would be greatly appreciated.