engine cranks but does not start, will start with starting fluid and usually stay running,then runs fine. sometimes not. replaced fuel relay,throttle position sensor,and air intake temp sensor. It may start and run fine for a few days then no start again. No fuel pump "whirll" when key is turned at times of no start. ANY ideas where issue may be ?

 

We could come up with a list a mile long as to possibly why a vehicle won't start.
Something to try if you haven't tried it yet. Turn the key on and off a few times and see if the starting improves. It could be something as simple as an ignition switch assy.

 

When the vehicle will not start, go to the Inertia (fuel cut off) switch to see if power is on both sides of the connection when the key is on. If both sides have current, possibly the fuel pump is failing.

 

the ignition switch is hard to turn.going out of town for a few days will check into that issue upon return thanks for the help.