VERY rough idle

[all4ford]

I have a 95 Explorer with a 4.0L 6 cylinder OHV . The idle is very rough when hot or cold. The exhaust smell is really heavy, not really like raw fuel or oil burning. This morning when trying to start it sounded like it backfired a bit.
I have checked the voltage to the IAC valve and get 11.5 volts on the plug. The resistance is 9.5 ohms across the 2 pins of the IAC valve, and no shorts to the case. I also have cleaned the IAC valve with carb. cleaner with no results.
I have checked for vacuum leaks but cannot hear any. Is it possible I have leaks at the intake manifold? How can I test?
There are no check engine lights associated with the rough idle either. Can someone tell me how to test the ignition coils on this vehicle? Any other ideas would be greatly appreciated.
Will try new plug wires this weekend.
Thanks!

 

[410Fortune]

Clean your mass air sensor first and fore most, then reset the computer.

Do a search for these proceedures.
This is the first thing to try when there is a stumble or miss at idle.

 

[all4ford]

May have found the problem

Thanks for the prompt reply and advice 410Fortune. I was checking once again for vacuum leaks and decided to start looking near at the EGR valve due to the "heavy" exhaust smell. I noticed some really tiny cracks at the top of the valve where the metal has rotted away. I brushed the part number sticker so I could get the number and the whole top is rotted off of the rest of the valve. The top (diaphram) part of the valve lifts right off. The hard part now will be to get the metal tube free from the EGR valve without twisting or crushing it.
I would have though I would have gotten some type of CEL though. Will post the results when I figure out how to get it changed.
Thanks again!