1990 Plymouth Laser starting problems

Hi my name is Frank I just got a 1990 plymouth laser 2.0 turbo engine U with a DOHC 16 valve (91kmillage) and I cant start it it wont start with the key I have too push it for it to start I have replaced the ECU, sparkplugs, the timeing is on, the fuel is in order same with the spark im gettin air I dont know what wrong with the car I think it might be the throttle position sensor or the fuel regulator I just dont know what to do im hopeing some one can tell me what wroung.