TBI 5.7 Woes

[JCampbell]

Having issues with the TBI 5.7 in my Suburban. Had a part-throttle ping, replaced the EGR solenoid and double checked that base timing was at 0°. Ping went away for about 100 miles or so (or maybe I just didn’t notice it), then came back. Thought it could have been poor gas, so I filled up with ½ tank of 91 octane instead of 87 to see if it would cure it. It did...I think. Tank ran out, went back to 87 octane, ping came back. Ran that tank out, filled back up with 91. No issues except yesterday at a stop light, the truck was idling, then stumbled slightly. It recovered quickly, but was sort of odd and seemed to come out of nowhere.

I jumped in today to head off to work, SES light came on. Truck seemed “sluggish” (could have just been in my head - the thing is on 35’s with 3.73s so it’s not exactly a powerhouse anyway). Stopped for coffee, shut truck off. Came out, started truck back up, SES light was off. Drove another mile (or so) SES light came back on.

Haven’t pulled a code or anything yet. Just wondering if anyone has any ideas?