new truck weard issue

[altereddezignz]

Ok guys i bought another truck. and here goes the question. It is a 90 model swb 2wd Chevy 1500 with a 350. Now it is pinging really bad. I found that the dist was not working properly so i replaced it and now it advances and so on normally. It is set to O adv with plug unplugged at idle is about 550. Shut off truck and plug in plug. Start it back up and it is advanced to 17 and idles at 775-825.. Not even after changing this it still pings or labor knocks bad. also it is 27 degrees advanced at 2800 rpm no load. So i noticed that the cat was stopping up and getting really hot so i had all new exhaust put on the truck. $0 series flow with turn down. no cat.
Next i tired unplugging the o2 sensor, still pings.
Tired unplugging the computer temp sensor to load it up with fuel - no change
it had a ruff idle.
in gear the idle is a lot lower and if u turn air on it will almost kill the truck.
Ran all but very little gas out of tank and put in 93 octane. No change.
Ran top end cleaner through the engine through intake - no change.

Can any one help. truck has 160 thou miles on it with no using oil records of every oil change at 3000 since brand new. no smoke, new plugs cap rotor and wires.

Thanks

[60ratrod]

sounds like there's a vacuum leak in there some where. the bushings on the throttle shaft tend to get worn out and allow more air by causing a vacuum leak. that's a common issue with these older tbi units. so i would start checking for leaks.

[altereddezignz]

if it was a vacuum leak i would ahve a high idle. I have sprayed all oer the intake with carb cleaner to check for a leak and am not able o find one

[GASoline71]

Did you try higher octane fuel?

Gary

[altereddezignz]

yes after i put 93 full tank i put in 101 at half tank, no change

[hayhauler71]

Did you check fuel pressure and volume

[dwcsr]

Have you checked to see if the knock sensor it connected or working.

[altereddezignz]

Gonno trya nd check the fuel pressure this afternoon and it is getting hooked up to a scanner to check the knock sensor but it is plugged up.

Also left my house this morning and it ran perfectly fine, got on the interstate running about 65 in overdrive and with the same pressure on the gas peddle it was like it kinda started loosing a little power and then started pinging. So i shifted it back into drive like i normally do and was back tot eh slight pinging????? this was a total of about maybe 3 -4 minuites when it started l;loosing a little power on interstate.

[altereddezignz]

ok cyl 2-4-6-8 have between 60-90 psi compression, cyl 1 ha3 60-90 3has 30 5 has 0 and 7 had 60-90..
Think i have some burnt valves..