99 Astro losing power up hills

[sharkmonkey]

Looking for advice. My brother has a '99 Astro van v6, 2wd and the motor sounds like it is missing when going up hills. I haven't actually touched the van but this is what he has told me over the phone:

He replaced the plugs, wires and cap. He's pretty sure all of the vacuum hoses are connected. He said it sounds like it's pinging like the timing is retarded when under heavy load, or going up hills. It doesn't look like the distributor can be adjusted.

I have all the tools but before I go visit him, I'd like to know what else I can do to troubleshoot. Any help would be appreciated. I can also ask him more questions over the phone too if that will help narrow it down.
-mark

[Blue Bowtie]

Any error codes?

Has the fuel pressure been tested under load? How about fuel pressure leakdown after shutoff? Is the oxygen sensor fresh?

[sharkmonkey]

Thanks. I'll ask if any of that was checked.
-mark

[procaddytech]

Loss of power and pinging does sound like a lean condition. A malfunctioning or restricted EGR can also cause pinging as will excessive carbon build up.

[danielsatur]

When you put the pedal to the metal going up hill will the automatic transmission step down?