Astro Idle issue

Hi all, I have a 95 Astro, 4.3L motor that develeoped a "loping idle". It has a steady surge that lasts about 1 second. To describe it would be a thrum..thrum...thrum at idle in neutral. I don't have alot of time to Dx, because i'm supposed to leave town day after tomorrow. Thanks for your advice..
Steve

Hi all, I have a 95 Astro, 4.3L motor that develeoped a "loping idle". It has a steady surge that lasts about 1 second. To describe it would be a thrum..thrum...thrum at idle in neutral. I don't have alot of time to Dx, because i'm supposed to leave town day after tomorrow. Thanks for your advice..
Steve
On Weds. the engine ran rough and a code 32 "EGR" showed up. I pulled the EGR and found a piece of carbon rolling around so I think the weird idle was caused by this.

That would cause it for sure. Did you replace the EGR or just remove it and get the carbon out?

I'd recommend you get a can of the aerosol version of the GM Top Engine Cleaner and run that through your engine. It will clean up alot of that carbon.

That would cause it for sure. Did you replace the EGR or just remove it and get the carbon out?

I'd recommend you get a can of the aerosol version of the GM Top Engine Cleaner and run that through your engine. It will clean up alot of that carbon.
Yes I just cleaned it. this is the second episode. I seem to remember someone talking about a EGR gasket with a screen to block the carbon. If i can find one I'll get it and keep it for the next time. The top end cleaner sounds like a good trick too.

That gasket with a screen will help keep the carbon from damaging the EGR vavle. I put one on my van too.

Get the aerosol version of the Top Engine Cleaner or if you can get that I also recommend Mopar's Combustion Chamber Conditioner, get it at any Chrysler, Dodge etc...