97 gm 350 vortec #5 cylinder misfire.new plugs,wires,cap?

If that fuel pressure spec was under load, that looks good to me. How long since a tune-up?
As far as a spark misfire, you can use a digital multimeter, engine idling, touch each spark plug wire one at a time. The readings I've seen is around .6 or .7 volts, but, if you get a reading bouncing off zero, that's where you start testing. You don't take spark plug wire loose and you don't penetrate the plug insulation, you just touch it with meter lead. It's an inductive reading.
There are several things that can cause misfire, fuel--spark--compression. You might do a cylinder balance test, engine idling, kill cylinders one at a time, if you kill a cylinder that has no effect on the rpms, that cylinder is dead or very weak. If you kill spark for this test, do it quickly, so you don't flood the cylinder.
The basics for a problem at higher rpms, check for blockage of some kind. The first two things I think of are fuel and exhaust.

Do you mean p0303? And on a gm 4.3l V6? If so this is a cylinder 3 misfire. Cylinder 3 is the back drivers side cylinder. You will need to check the plug and wire. A compression test to rule out any I ternary problem would be advisable as well. Compression test needs to be done on all 6 cylinders. The results should fall in a range of +/- 10%. There are tons of causes for this from ignition module, wire, plug, injector or fuel delivery, bad map/maf sensor, valves problem, ring problem etc.

If you replaced the plug, wire and cap then it's either gona be the intake gasket seeping or a bad valve. Gasket more than likely I'd say bc the vortec motors are really bad about leaking or blowing the lower intake gaskets

Check your coil pack. Sounds like one or two need replacing.

You didn't post your engine size so please use the appropriate diagram:




GM (Cadillac) 250 (4.1L) V8 .GM (Cadillac) 273 (4.5L) V8 .GM (Oldsmobile) 307 (5.0L) V8 .GM (Oldsmobile) 350 (5.7L) V8 w/EFI.Engine firing order: 1-8-4-3-6-5-7-2 .Distributor rotation: counterclockwise





GM (Buick) 252 (4.1L) V6 .Engine firing order: 1-6-5-4-3-2.Distributor rotation: clockwise





GM (Cadillac) 368, 425, 472, 500 V8.Engine firing order: 1-5-6-3-4-2-7-8.Distributor rotation: clockwise





GM (Cadillac) 429 V8.Engine firing order: 1-8-7-2-6-5-4-3.Distributor rotation: clockwise

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Here is a wiring diagram from distributor cap to spark plugs. the firing order is 1-8-4-3-6-5-7-2. I hope this helps you.

could be burnt valves or bad plugs or bad wires or distributor cap

These have a real problem with the distributor caps, i would try that

hi there, if you can feel the misfire at an idle but not at a higher rpm than the fuel pressure regulator is bad im working on one right now that has mifire code and random misfire codes coming up