I am new to the site. I have a 92 GMC Sierra 1500 5.7. Just got the new motor and trans put in. Motor bored to a 355 converted to a Roller Cam motor with:
Stock 96 Vortec Heads studded but unported
Comp Cams Complete Kit with the 258HR Cam
SpeedPro Forged Pistons
Stock Crank (Turned 10/10) stock reconditioned rods
Comp Ultra ProMangum Roller Rockers
Stock tbi, just cleaned it up
Stock Computer
Magnaflow Spun Catalyic Converter
Magnaflow 3in in/ 2 1/2 outs
Stock 3.42 gear
Rebuilt with better clutches and bands and bigger drum 700r4 Trans
Stock Converter

High Performance In-Line Electric Fuel Pump12 Volt
12-17 PSI
50-58 GPH (190-220 LPH)
Inlet/Outlet: 5/16" Barb

I am very impressed with the build first off. Truck runs good when it is warmed up. I notice it stumbles in 2nd when I am on the gas at quarter throttle. Not sure if it's good too much gas or not enough. The truck moves good when I am around 50 mph and above. My fuel pump is listed above. I figured I need a tune. I though about Jets Custom Chip. They said $500 since I changed the Cam. My mechanic said I need a Dynotune to get the bugs out.

What do you'll think? What should my next steps be? It is my daily driver. I want to clean up issues and make it run clean and open throttle.

I saw Dave W said he recommend the 94-95 gmc computer with the red and blue connectors. I found two of them for $69 each. Also I saw about the 670 Cfm throttle body. Why these two pieces?

thanks for any help.