MK2 Tuners VW GTI 1.8 16v

I will give anyone 300.00 to get this running. A wiring job has been done, new harness, digifant 2 ECU and all I just ran into a glitch and I can’t get it going more than it will start, start missing and die. It is a engine replacement job. I’m just missing something. Electronic people know more than me. Help. Fuel delivery issues ? I don’t know. North of Chicago 16 miles.