Rattle whenever engine is high rpms then gas is let off

[cp2295]

One of the immediate fuel saving benefits fuel injection brought to the table was the ability to shut off fuel flow when it wasn't needed.

When you take your foot off the gas pedal the injectors are shut off, if engine is above 1,500rpms, with a carb any air flow sucked fuel out of the jets, so coasting down a hill in gear cost you money.

If you don't push down on the gas pedal again the injectors come back on, at "idle levels", at around 1,200rpms.

So there should not be any backfires unless some fuel is leaking in to the intake.
I would check that TPS is below 1volt with throttle closed.
And if possible check fuel pressure with engine on then with key off to see if it is dropping way down, i.e. a leaky injector.

I just checked the tps and it's at .95v at closed throttle, 4.8 at full throttle, I haven't checked the fuel pressure will do tomorrow