Try reset your IAC
http://www.ehow.com/how_7959677_rese...le-gm-tbi.html
Might want to invest in a data logger if you plan to keep it for much longer
http://www.moates.net/
Good forum on how to tune a TBI.
http://www.gearhead-efi.com/Fuel-Injection/forum.php
Wish I had a 454 in my 89 V2500.