Rough idle, steady RPMs

[RCSB]

Hello, I am trying to fix an idle issue that i have in my 95. Cold or warm there is a stumble at idle with little to no change in RPMs. I have changed plugs/wires/cap/rotor/fuel filter/Balancer. Timing is set to 10* BTDC. I also cleaned the MAF and Throttle body. No codes KOEO. I got a code 31(EGR) with KOER but it only came up once. Ran cylinder balance test and it was good(code 9). I sprayed carb cleaner to check for vacuum leaks and was unable to find any. Should i look further into the EGR code even though it only came up once? What else should i check? Thanks.

 

[ttocs]

Get a fuel pressure gauge to slap on the schrader valve on the rail. How old is the pump?

 

[RCSB]

Ok, ill have to buy one. It runs good though, just have this issue at idle. No idea on the age, i just bought the car a few months ago, it has 175k miles.