'97 SL1 Engine Hiccup

First, a bit of background... Step father (decent mechanic, but not an expert) scanned for codes on the car a few weeks ago (he just does stuff like that). It showed EGR, O2, CPS, and maybe coolant temp(not sure on my memory here). He pulled off the EGR valve, it wasn't moving freely so he cleaned it with some carburetor. We weren't going to worry about the CPS or the coolant temp. The O2 was going to be saved for a later date.

A couple of days later the car wouldn't start. I checked the forum here, found people talking about the CPS... found an awesome guy on youtube that showed me a test for it. The test showed it was the problem. I replaced it, and the car runs.

BUT... and this is why I'm here... there's now a hiccup in the engine. At idle the engine will almost drop into a stall, and at speed you can notice a brief hitch before picking back up.

ideas?

Replace your coolant temp sensor

Make sure that you don't have a intake leak, s cars are notorious for it.

Make sure that you don't have a intake leak, s cars are notorious for it.

Not really so common on the 2nd gen s-series.

Not really so common on the 2nd gen s-series.
no, but I still change them a lot

Replace your Temp Sensor. The stock sensors that came with the car are notorious for failing. I think the stock is only plastic, but the replacement is actually brass (if I remember correctly when I changed mine). **Brilliant idea on GMs part**
These S-series Saturns are VERY finicky when it comes to the Temp of the coolant. It will make a big difference if that sensor is bad or even if your fluid is just a millimeter low.
Also it might be worth the short time it takes to replace the O2 sensor. But it depends on which one is it. These cars have 2. I replaced the Front O2, took only about 15 minutes. It did help my Saturn (97 SL2) run a little better.
Search on this forum for information regarding that Temp Sensor - you’ll find tons of information.
Good Luck!