03 Sonoma /w 4.3 runs and doesnt ?

changed my fuel pump about 6 months ago when it wouldnt start at all... truck ran fine for about 5 months and now it runs okay sometimes and others it will not start without really time and again turning over ? My mechanic said to try and turn the key on and off three time and see what happens... yesterday had it parked in the driveway and it would not start but when I did as he suggested it started right up as FI does ! Sometimes I will be driving ritght along and it will stall and in order to get it started again i have to turn it over and over intermitently. It will run good for a week or more and then cause the problem. Any sugestions are appreciated (changed the filter too ) ???? is there a relay that could be bad ??

changed my fuel pump about 6 months ago when it wouldnt start at all... truck ran fine for about 5 months and now it runs okay sometimes and others it will not start without really time and again turning over ? My mechanic said to try and turn the key on and off three time and see what happens... yesterday had it parked in the driveway and it would not start but when I did as he suggested it started right up as FI does ! Sometimes I will be driving ritght along and it will stall and in order to get it started again i have to turn it over and over intermitently. It will run good for a week or more and then cause the problem. Any sugestions are appreciated (changed the filter too ) ???? is there a relay that could be bad ??

Get a fuel pressure gauge on it and check fuel pressure when it acts up and see if it is up to specs.
Or better yet put a pressure gauge on it and tape gauge to outside mirrow or windshield and watch fuel pressure when running on road and starting and when it acts up.
Post back fuel pressure readings.

What brand fuel pump did you put in it?