Got a 97 sidekick that developed a very rough idle.  Warmed up the vehicle, ran fine, about a mile down the road started to idle real rough.  feels like it is not running on all 4 cylinders cause there is a definite loss of power as well.   

History:
New timing belt about 1yr ago,
Replaced distributor orings at same time and they made a line/mark on the dist. which has not moved or slipped.(Im assuming the timing is good but have not checked with a light)
New spark plugs 3mo ago
New wires and dist cap/rotor 4mo ago(I am assuming it is not these also)

Did a Obd2 scan
The only codes that came up were :
Pending P0400 Exhaust Gas Recirculation Flow and
Stored P0400 Exhaust Gas Recirculation Flow
These I already new about, this is an old problem that I have not got around to fixing yet and Im pretty sure It is the EGR passages need to be cleaned out.  So I guess whatever is causing the rough idle is something that would not cause a code to be stored.  Tell me cause I might be wrong, that would rule out plugs, wires, cap and rotor , right? They should set a misfire code I thought.

The freeze frame data from the scan gave me this info which maybe a suzuki technician can make more sense of for me.
DTC for which freeze frame was stored--P0400
Fuel system 1 status   ---------------------- Open loop, due to driving conditions
Fuel system 2 status   ---------------------- Not supported
Calculated Load value----------------------- 12.16%
Eng Coolant temp----------------------------185 deg F
Short term fuel trim-------------------------0.00%
Long term fuel trim--------------------------2.34%
Intake Manifold  Abs pressure------------6.20 inHg
Eng RPM----------------------------------------1537
Vehicle Speed Sensor----------------------29.83mph

I had a spark plug wire come loose once and the eng behaved very similar but all plug wires are tight this time.  I am leaning towards a fuel injector ? What does Open Loop mean on Fuel system 1?  Is that normal? Hopefully one of you can help me... Thanks

Moatmonster

Carfully pull one wire at a time. Like pull cyl. 1, run motor. is it the same and no worse? then the problem is with one cyl. If it's worse replace wire & go to cyl. #2 and down the line. This simple test will tell you if it's a problem with one cyl. or something else. If all the cyl.s are working the poss. cause maybe a EGR valve stuck part open . This can be checked by touching the metal tube from EGR valve to intake as the intake tube should be no hotter than the intake manifold if it's "closed" as it should be at idle. If at idle the EGR tube is hot, exh. is getting into the intake & poor idle or stalling will happen. Lastly consiter vac. leak. This can be  checked by spraying brake/parts cleaner around intake system & if idle go's up. Bingo! you have found the problem. Hope these few Ideas help as I don't fix veh's like this on the internet with limited input. Good luck.

I had a fuel pressure regulator give me a rough idle.

Pull the small hose off the regulator while it's running and see if it drips gas. It could be loading up on you.

FYI: the fuel pressure regulator is right by the thermostat housing. 

It isn't cheap either. 

I've also heard that the vaacuum lines on the EGR will crack. I'm sure that would throw a code too.

 FIXED IT!!!! I pulled one spark plug at a time like was recommended. Thanks!!! All of them made it run worse except #2  so I pulled the spark plug but it looked fine.  I looked at the insulated part of the spark plug wire  that goes into the valve cover and there was a very small mark with a pinhole that apparently the spark was grounding to the valve cover instead of the plug like it should.  Shew!!!  I am glad thats all it was because Autozones fuel injectors are $ 489.00. Crazy!!!! Anyway I wrapped some electrical tape around it to insulate it until I can get to the store for better spark wires. 
Thanks for the help.

p.s. Dont assume anything!!!

Glad it was a cheap fix!

I know Ele tape is a "bandaid", but it's one that can last for a long time.