One should first isolate the cause of this problem by testing the trigger reset with the slide removed. Remove slide assembly; pull trigger; while holding trigger back push the trigger connector sideways to simulate the slide pushing it during cycling; release trigger while closely observing and feeling the reset.
Next test the striker block safety. Remove striker and its retaining back plate from the slide. Push the striker block safety in at an angle, being sure you push in from the side that the key on the trigger bar pushes it. Observe its degree of grittiness as your pressure on it is released.
Next test, put the slide assembly back on the gun without the striker and its back plate. Looking through the back of the slide with a flash light, observe the alighnment that the key on the trigger bar hits the striker block safety when the trigger is pulled.
JWH321, that was good call to mention the trigger safety as one possible cause of the problem.