Hey there, with everything you replaced I'd be willing to bet it's the PCM, if you knew someone who would let you borrow one you could find out. The reason that's my guess is I read a while back that when an injector goes bad after a while it burns out the PCM controls then the injector stays open or partly even when the engines not running. If you want to check take the upper plenium off remove an injector from the intake be careful & get a friend to switch the truck don't crank it just switch it make the fuel pump run, if any of the injectors run or trickel it's probably the PCM or ECM think there the same thing. Let me know what you find out. Sorry I didn't notice that you said the previous owner had tried a PCM but sense you replaced the spider after he tried that I would go ahead and try another PCM again it can't hurt.

 

 

You most likely have plugged catalytic converters

 

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Yes the spyder bracket is supposed to be loose . That helps it fit through the plastic intake when you put it back on.So let it be loose.

 

The time is off . You can move the cap a small amount by just loosening the clamp on it , if that doesn’t work you are off by a tooth or more and you will need to pull the shaft up /out turn it and drop it back in. You must have a GM compatible box to set the time . You can get close enough to do what your is doing then put the machine on it to get it right it’s a must.