I have a 1986 chevy s10 2 dr std standard cab sb and I had to replace the engine ,I put a 1991 s10 motor in it but having problem with tbi

I have a 1986 chevy s10 2 dr std standard cab sb and I had to replace the engine ,I put a 1991 s10 motor in it but having problem with tbi My friend keith swaped it out for me he said the 91 tb did not have the right hook ups for my 86 truck so he put the 91 on and somehow made it work , well I went thru emmision testing and failed they said all my other readings were great but I failed the hydrocarbons it was too high he said to tell my mechcanic it was running too lean he said since all the other readings were good that it would probaly be a repair nota replace so now i took it to another friend of mine  because he only lives about a mile from me now he said he believes it is because of the tb and that i should get a 1991 tb and it should probaly fix the problem . I would like your opinion on it . it is my only transporation and I need so very bad  with putting in the engine and all the other parts  i need to get it running correctly and very depenable hopfully with not too much more expense I am on the road quite often locally but in phoenix that is alot of miles I am single and almost always drive alone. I have always cared for my vechiles I believe that if you take care of them they will take care of you ...and that has been pretty much true my whole life ...that is why it is soo important to get my truck running right  so any ideas you may have would help me greatly....THANK YOU SO MUCH FOR YOUR TIME AND HAVE A GREAT DAY!