Suzuki: 97 Suzuki Sidekick, vacuum control, suzuki sidekick

Question
I bought a "great running" 97 Suzuki Sidekick 5 spd for back road 4 wheeling in the Idaho Mountains, we nugget hunt the old mines.

The engine light came on within 5 miles after the purchase but still ran perfect. Light indicated the EGR valve was bad, immediately after being replaced the engine ran bad 'poor idle' & the engine started smoking & developed a rattle ??
I'm an old-school pre-computer mechanic, this issue with the EGR valve has me over a barrel.
Any idea what is going on & how I solve this problem ?
Thanks in advance for this website & any tips you may have.
Chuck

Answer
To start, unplug the hose to the egr valve.  It should not have any vacuum at idle.  Did it solve the problem with lousy idle?  If so suspect a problem in the control system.  Put the old one back in.  Did the problem with performance go away?  Are you certain the new valve is the correct one?  Is it visually identical?  It's not all that unusual to get the wrong part the first try....

Something to be VERY aware of, is that the trouble codes will point to a problem in the egr SYSTEM, and it isn't always the valve, it could be a wiring or vacuum control valve problem causing the egr valve to operate at the wrong time, and the valve itself may well be faultless......The codes only tell what SYSTEM is causing the code to set, but NOT WHICH DEVICE, PROPER IS MALFUNCTIONING.

I'm not that familiar with late stuff - all my vehicles are samurais, and about ten years older. Samurais are my specialty field, and i can only do generalized advice on later vehicles.
I don't have any literature on later vehicles

Go to iatn.net, and use the shopfinder on the first page.  You can find a tech in your area that way.  The iatn network has many hundreds of thousands of years of cumulative experience.