Code 45 surging at idle when warm

[MusketStyle]

Hey guys I don't post a lot because my K5 is generally really good to me, but not recently. I have an 88 K5 TBI 350 AUTO. As the title suggests it bobbles and surges pretty hard once warmed up and at idle. Runs fine and CEL goes away soon as I start moving again. I have replaced the following in the past year, complete distributor, O2 sensor with AC Delco, coil, plugs, temp sensor (both), MAP sensor and alternator and rebuilt the TBI in an attempt to solve the issue...

I'm completely stumped.

Next step fi-tech fuel injection (sort of kidding.... Sort of)

Any help would be greatly appreciated.

 

[MusketStyle]

I have a YouTube video of the tach freaking out at a light after driving for 20 minutes

 

[Fordum]

Wild Guess, EGR valve sticking.

 

[MusketStyle]

That does seem like the only thing left other than injectors which appears to be spraying properly

 

[Fordum]

Well, code 45 is low oxygen content in the exhaust, which normally indicates a rich condition. However, I'm pretty sure dumping exhaust back into the intake when the computer was not expecting it, would displace some of the oxygen that would normally be sucked in, and fool the computer into thinking too rich.

I know those valves can get coked up and give problems.

 

[MusketStyle]

Took some time today and played with this and that... Turns out the EGR valve is 100% shot. I can blow air through it with my lungs... Ordered a new AC Delco replacement. Should be here Wednesday. Will update after installing