Guys the engine i had put in is giving me loads of problems.

Idle problem is bugging me as i cant find the problem anywhere

its up and down hot or cold but until last week it only did it when cold

i have removed and cleaned the iscv but no joy

i noticed under the throttle body there is a small pipe with a bolt in the end of it?? its blocking off a air inlet,when i remove it it sucks air and the revs go up?? it looks like its home made...what is ment to be there and is this causing me any problems?

Please Help