"NEED HELP" 2000 GMC starting problem

[bab2000]

Hello Has anyone had this problem

I have a 2000 GMC Sierra 1500 4.8 4x4.

My truck at random times will crank and not start and when it finally starts it seems to run fine with no issues.

The times between no stating are so random it could be the next time I try to start it or several times later or even days later.

I thought it was the crank position sensor, fuel filter, fuel regulator, and fuel pump, I changed all of the none worked 

Why I think its something to do with fuel because when it doesn't start if I spray starter fluid into intake my truck will start and run until the fluid burns off.

 

One other thing, this started after I got my truck back from my mechanic. I was having an electrical transmission issue, That they fixed then this started. I did talk to them and it sounds like crank sensor or fuel pump. i didn't take it back because I thought it was something simple and didn't want my truck gone again.

the issue was a code p1870 transmission component slipping.

there was a problem with the computer not locking up the torque converter. so they was a bad brake switch, neutral safety switch, ignition wires, and computer

yes it's an old truck but you got to love it. 

 

I'm stuck. Does anyone have an idea what it could be?

 

thanks

 

[dna9656]

Fuel pump relay? IAC? Throttle position sensor? Intermittent signal from oil pressure sender to fuel pump? These are my Wild ass guesses. there are guys here that will be able to do more than guess, they can make  Scientific Wild Ass Guesses because they work at GM dealers!

[bab2000]

Thanks dna9656,

Those are a few things i was think to check next 

I also thought spark plugs,

Or injectors, im going to do a compression test just to see. Bit it weird when it starts it runs fine as much as i can tell.

Thanks again