It's a riddle

[Hybrid]

Hey guys for those of you who know me, this is Jacob and I still have a tbi problem!! I can't get this 350 to run right. I have installed a tbi system with a brand new wiring harness, and i couldn't get it to run right so i started replacing things, like knock sensor, coil inside the distributor, and the harmonic balancer. When i pull the ground on the computer to set the timing to zero while on TDC it is really really hard to get it to zero without it stalling. Then when i get it pretty close i reconnect the ground and fire it back up. It will run really nice for a little while, but when it warms up the rpm's drop gradually until it eventually stalls. Oh and I have also checked the ECM and it works great when hooked up to another rig. If you guys have an answer to this riddle please let me know. Thanks