I have an 89 motorhome with a 460 engine with carb. Would it be better to have the egr valve capped off or to have the vaccum coming from the front of the carb or the manifold intake? Would the engine run cooler with it capped off? Having trouble with the engine dying when I let off the gas reminds me of a vapor lock. I do have a return line on the gas line so the gas should circulate. Don't know if this could be coming from the egr valve or not.

 

It will run cooler with the EGR hooked up. That's it's purpose, to effectively richen the mixture by reducing the amount of oxygen in the incoming charge.

My engine is running ported vacuum (from the top of the carburetor) through the thermal vacuum control valve.

*Could the EGR cause a stumble, or the engine to die?*
Yes.

But you don't say anything about how it is sealing or whether it is operating properly now.
You will need to do some tuning if you choose to disable it.

 

ArdWrknTrk, That is the problem I don't know if it is opening now or not. I think I have it hooked up the right way. I had to put a new intake gasket on and the vacuum hoses was not hooked up properly. I hooked them the way I thought was right and been having trouble with it dying ever since. It seems to be running a little bit hotter than it was before. So I am wondering should I hook a direct vacuum to it to try. When I hook a direct vacuum at idle it changes the way it idles. Going to the Blue Ridge Pkwy in the morning any help would be appreciated.

 

Sorry if I went to sleep, as it's morning now.

If it doesn't run right and you need to drive unhook it and cap the vacuum line.
Deal with it when you can.