97 SE 3800 SII. 188K miles.
I let her warm up for 20 minutes today. It was about 10F here in Michigan. Has been running a little rough at idle through the outrageous winter we've had but no 'service engine light' in 3 years til today. I drove about 1-2 miles and pulled up to a stoplight. My tachometer started suddenly fluctuating wildly between 500-1500 RPMs and the service engine light came on. I thought she was going to stall. Never stalled but that might be because I kept throwing her in neutral and revving up to 1000 rpm at idle until green light. Plenty of power so long as I had my foot on the gas but going back to idle caused massive fluctuations in RPMs. Nailed the throttle a couple times up to 80 mph on the freeway, tiny bit of hesitation when applying throttle from dead stop but no chugging/sputtering so long as my foot was on the gas. Fluids all look good, nothing dripping underneath.
Got codes scanned by my mechanic. EGR related code and also an 02 sensor related code. Having them inspect the engine for any signs of a larger problem that might have erroneously set a code for both components. They're not always very up front about what's going on.
Wondering what this means for both the EGR and 02 sensor to set a code at the same time. Anyone else able to draw a correlation between the two?
I appreciate your advice tremendously. After I resolve this issue I can help less experienced forum members like myself with the same issue.
