A pinging sound only under a load

Naaa not water, the low octane fuel. If you had water in the fuel your motor would cut out and stall or not run at all and if cold enough it would freeze in the fuel line and maybe other places too.

So would low octane cause a rough idle and pinging like its overheating but nt overheating

Sure it would, you should run atleast min grade fuel in an older car or truck and it wouldn't be a bad idea to replace the fuel filter if you haven't done so. It could save your fuel pump by replacing it.
Keep in mind about the knock sensor, it compensates for low octane fuel.

I hve replced the fuel filter already and the knock sensor hasnt been hooked up since I hve had it almost 9yrs

Is the knock sensor above the starter just want to mke sure

Ok, I thought you did, as for the knock sensor location I'm not sure. They tend to put them in different places. I've seen them on the sides of the motor around the motor mount and they also put them on the heads too. They even use different ones on the same motor and year design. If replacing you may even have to see the shaft on them to know, like some are 5/8 and some are 3/8 shaft where it mounts. I guess it has to do with where they locate it and the available predrilled hole, anything to save money. LOL
If you have the repair manual on this, see if it helps or if you’re still having trouble finding it I’ll do some research and see what I come up with...
Dave

Ty I just dnt know what else it could be was running great till I filled up with gas and now this I have a total of bt 500.00 already I dnt have a repair manual on it

Well if you decide to keep it and money is tight you'll need one to work on it. That's one of those must have tools. You think you have troubles, you should see my post here on the 98 astro won't start, no help so far.
You have enough to check on for now, look it over and get back with us out here, everyone that reads these posts needs help.

The plugs are gapped at 35 whats wrong with the astro whats it doin

Vette, you have even more to check on now sparkplugs, if they are the wrong heat range like rasmataz said it could cause the pre-ignition or ping too just another possibility. Astro link
https://www.2carpros.com/questions/1998-chevrolet-astro-won-t-start-good-spark-fuel-pcm
I’ll check back tomorrow and see where you’re at. . .
Dave

These are new plugs and they are the rght ones for it

Get a what

I just replaced the egr vale and thats not it either now back to square 1 again

Hi Vette, where we at, new egr valve was there alot of carbon build up, same trouble? Did you run any other tests?
The expert wanted you to run exhaust tests but only way you can do that is to take it to a dealer or someone with the right emission tester machine. I think he is upset that I’m out here with my input.
I’ll help you were and when I can, I’m not paid to help but the experts here are with donations and ads.
Dave
I’ll help you were and when I can, I’m not paid to help but the experts here are with donations.
Dave

Just a litte bit

The timing is rght it still has a rough idle litte hestition off the throttle and pinging only under a load

Thank you for info I wish I could donate but I cant rgt nw sorry

Ok, So the timing is right, I hope you got the right specs. What was it BTW?
While you were checking timing how was the engine idling fast, slow etc. And did you see the timing mark jumping around on the damper pulley? And by chance did you rev the motor while the timing light was on?
I’m asking these questions because base on the answers the timing chain may have play in it...
Re: knock sensor, did you hook that back up?
Did you get any CEL’s today and if so what happen just before it did?