I have a 92 1500 2WD came stock with 305 TBI with 700R4 trans. It now has a 90 2500 454 TBI but still has the 305 computer and chip. The computer number is 16146299 with chip AWHC. With this setup the truck just isnt running correctly. It has what I would call a hesitation at low RPM's and like a surge. Once you get over 3,000 RPM's it seems to run ok. I unhooked the TEMP sensor just as a test to see if it was lean and it ran better. I'm thinking I need another chip or maybe even the whole ECM but not sure which one I need. Any help would be appreciated. P.S. This motor had a idle surge and after reading on the web I put a new ACDELCO pickup on it and set the timing on 12 Degrees with brown and black wire disconnected and it fixed the surge.