1997 5.0 Silverado missing no CEL

[Plinkin]

I've got a 1997 silverado with a 5.0 and an automatic transmission. My problem is that when I level of it has a miss that you can definitely feel, at idle it's pretty smooth and acceleration is decent but not great. So far I've change the spider injectors, fuel pump, fuel filter, coil, icm, distributor, rotary cap and button, plugs and wires gapped myself, crank shaft ps. I was getting a vel that said random multiple missfire but it went away after I changed a few of these listed above but the problem still remains. I'm fairly certain the fuel pressure is good 55psi after that I'm at a loss as to what to check next. I've ordered a 2 book service manual so I can start checking the resistance and volts of sensors. This has been going on for a few months and hasn't changed. It used to break the tires loose in the back pretty easy, now it just revs up. The truck has 190000 or its a mpi 5.0 with a automatic transmission. Thank you.

[Plinkin]

Ok small fuel update, not sure if this is relevant to the problem. Fuel pressures: idle 48 psi, hard acceleration 55psi, constant throttle leveled at a speed 45-48 psi, cycling the key on and off reads 55 and the jumps to 51 psi after a second or so and drop is not gradual.

[speedygonzales]

Do you have a cat convertor?

EGR not closing all the way

Check compression on all cylinders

[Plinkin]

Yes I do have a cat I've been meaning to stop by a muffler shop and have them test it. How would I test the egr?

[Kudzupatch]

Just because parts are new doesn't mean they are good. I have replaced an EGR and Plug Wires with new parts that were bad. Plug wires were causing similar symptoms and was hard to track down. It was arcing to ground but only intermittently.

[Tom]

Fuel pressure is too low, replace the fuel pump.

[speedygonzales]

Let's talk about a few things mentioned.

The easiest thing to check for an owner would be a cat converter. Just disconnect it and let it idle and then take it for a drive. Yeah it's loud but you can tell if things change.

However, I can't tell you how many people I've seen that dismissed a compression test DONE CORRECTLY that turned out to be bad. You should have done one in the beginning with an engine with that many miles on it. Get it done.

I don't think your replacement wires have the exact same problem as your original ones.

Just like I don't think your replacement fuel pump has the same exact problem your first one did. I think like dozens of other folks I've seen, your fuel pressure gauge is inaccurate. However, if you got the new style injectors, they operate at a lower pressure than the original poppet style. in fact 55-62. So that coupled with an inaccurate gauge. Badabing.

With regard to the EGR just take it off and look at the thing. You can tell if it's been sticking or held open. Clean the thing.

One last note on replacement parts that are crap. Yes they are getting worse by the day. If you use certain parts that are NOT OEM, you are asking for trouble. The fuel pump is a great example. If you buy a cheap auto parts store brand, you are in for pain. BUT for the replacement to give you the exact same problem as the original. Not likely.

[Tom]

48psi is too low regardless of how many pumps are put on. Verify that low reading is correct and then its either pump or pressure regulator.