I can only report what happened to me which is what the original post asked. Everyone knows how much of an expert I am. I had a fusebox issue (putting it mildly) the symptoms you outline are exactly what I ended up with. I was forced to get a diagnostic toy as I was stuck in southern Spain. The lambdas showed the lovely .447v etc. The maf showed a bit of movement on revving but barely reaching spec. New fusebox no difference but the magic lantern show disappeared. I cleaned the crud off all the contacts on the engine ECU and multi connectors.Marginal difference coincidental with maf element cleaning. Renewed lambdas and maf bosch from island. I'd previously bought two lambdas for 50 quid and a supposed Bosch maf element only. Reverted to original after running like a dog. I bought a gurenteed ECU from Germany and a synchmate. Synched with my heart in my mouth as I feared I'd wiped the becm out with the fusebox thing. I'd fluked that. Admittedly I carried out these measures out of shear desperation with help from landyzone, being a total ignoramus. It all worked in the end.the chain, therefore, is fusebox, ECU, MAF, lambdas and reset adaptive settings.that got me home through Spain, France and 300 miles UK. If you want to know how to do something wrong, I'm your man.