I swapped an HT383 stoker in my 98 Sierra in October of last year. I just put in a new exhaust last weekend with fresh cats (my old ones were burnt out) and I'm still running the same cold air intake I've had for about 3 years. I've heard mixed things about having to retune the computer for the bigger engine. I have not because it seems to run great with lots of power. After the new exhaust I'm getting a P0102 code for insufficient air through the filter. In the mornings when I'm leaving the driveway, the truck will bog down for about 10 seconds then pick up and runs like a new engine should. This never happened until I put the new exhaust on. I know for sure the MAF sensor is good. I'm woundering if my computer needs to be tuned for the bigger engine. Anybody got any suggestions before I start throwing money at possible but not likely causes?