Does anyone have any experience with symptoms of a failing lower wiring harness for a W140 Benz (1993 Benz 300SE)?

Although car runs well, am noticing an intermitten acceleration difference . . . sometimes peppy, sometimes not as peppy. Changed about every LH component associated w/ giving computer data so it can run the engine (i.e. MAF, O2 sensor, CIS sender, etc.). No fault codes are showing up on the tester.

Have also noticed that the IR does not function at times for only a few minutes after turning the engine off. I've changed the upper wiring harness years ago but noticed our forum colleagues as complaining about the lower harness with our W140 cars. I am attempting to ascertain if the IR response is somehow associated w/ the sluggishness experienced at times - potentially due to a short somewhere. Thanks.