problem with start and idle

[96GST16g]

so i just rebuilt my engine and now i come upon this problem it wasnt right away when i started it i put on about 70 miles and it occured when i rev the motor to about 1700-2500 it will not stay at a constant rpm... and it is really hard to start you have to hold the gas pedal down or it will not start i know it doesnt help fuel inj vehicles but it dont start with out it any ideas?