OK sorry. My bad. I was thinking of the butterfly valve on the 94 or 95 SR trucks. I see you have a 97 so there is no butterfly valve. I am talking about the butterfly valve on the intake manifold, not the one in the throttle body.

Once again, it sounds like an electrical/ignition problem to me. 8 year old wires is not good. Check the coil packs. Camshaft position sensor, crank position sensor.

The best fuel injector cleaner in a bottle is probably Chevron Techron.

How did the plugs look when you changed them? Any oily plugs?

How old is your timing belt? If it is original it may have stretched so much that your cam timing is off.