I recently rebuilt the TBI on the '91 Suburban and around that time, the engine started dieing and backfiring when starting the engine from cold. I'm not certain if it was doing this before I rebuilt the TBI, but I don't recall it. If I don't keep my foot on the accelerator, the engine dies almost immediately. When I keep my foot on the pedal, it will stay running, but backfires for about a minute until it starts running evenly. After that, the engine runs great with no misfires or loss of power. All the vacuum hoses appear to be intact. I'm not sure what issue would exist only when starting and for the first minute and then resolve itself. Any ideas? I feel like I should know where to go with this, but it's not making itself apparent to me.