I have a 97 K1500 with the 5.7. I just did the upper and lower intake manifold and replaced the fuel pressure regulator while I was at it. It now has a rough idle, misses and hesitates and is hard to get started. It will crank crank crank crank and the start up like its rebuilding fuel pressure.
The last time I checked the pressure was before the intake job and it was at 61 psi, but sometimes would shoot up to 61 then come right back down randomnly. Today I checked the plugs and found that the driver side was completely fouled out, but the passenger side where fine. Anyone have any ideas?

 

You need to pull the upper intake off. The spider unit must be leaking from a injector or the regulator. Its possible some injectors are not back in correctly.

 

Is it possible that the whole unit could be bad? What would be my best way of finding out? Could I just replace the injector if it is only the injectors?

 

Pull the upper intake, put the steel fuel lines back on the spider unit, then have someone cycle the key and look for a leak.

 

Pull the injectors out to?

 

No leave the injectors in just put the lines back on. You need to make sure it is only coming out of the end of the injector.

 

Well I replaced the fuel pump on it. After checking the pressure again. It would drop more than 10psi in 3 minutes after being turned off.. Fires right up now. Now I have a bigger problem I think. I can hear a gurgling noise coming from the heater core area, the truck overheats and the coolant is being pushed into the overflow bottle with air taking its place.....head gasket?