Alternator causing idle surge issue??

[ivorton74]

I had a friend of mine replace my head gaskets a few days ago and the truck runs better than it ever did since I put it in back in 2014...but still having idle surging. The thing is when my buddy started the truck after he put everything back together he realized he forgot to hook up the little red wire behind the alternator...he said the truck started idling really good...then when he put that wire back on it started surging. Today I tried what he did and he was right. So could there be something wrong with my alternator? I believe the one in the truck is a 105amp and my buddy thinks maybe I should switch to a 130amp alternator...what do u guys think? I've been having this issue since I put the motor in and it's driving me crazy