1990 Chevy Truck Wont Start

Hi guys,
I have a 1990 Chevy pickup with a 350 in it. The truck has been setting in my garage for approx 5 years. Recently I replaced the fuel tank, the sending unit fuel pump in the tank all the fuel lines etc.

I could not get 12 volts to the new fuel pump, I found a wiring hireness problem repaired it and the vehicle started. I let the truck sit for 2 days, went out to start it and now it wont start. If I put some gas down the carb, the truck starts and will stay running.

Could it be possible that the throttle positioning sensor is bad?

Thanks.