Ok, I already know the answer, but feel free to make your guess.
Modern configured but older car seems to have suddenly and for no clear reason lost much of its engine power and engine is misfiring so badly it is nearly un-driveable. New MAF, new fuel filter, no vacuum or exhaust leaks, new throttle position sensor. Same problem. Wiring, grounds all ok. Scan tool diagnosis shows nothing wrong, injectors injecting fine.
Diesel in the gas.
Distributor leaking oil internally into the cap.
Seriously George, need a bit more info. Would this happen to be a 92 Corolla?
Completely worn out engine…
But I need more information, you know the drill…
Year, make. model, miles, engine…
Nut behind the wheel??
Doubtful, because few people would own a scan tool that can work with this type of car. Also, the scan tool would provide limited troubleshooting data, and not include misfire data, fuel trims, etc.
Good guesses from those who ventured , but all incorrect. The EGR valve was stuck open. Citroen Berlingo.
Let’s see, last time I opened a hood on a Citroen, . . . In Europe don’t they double grantee them so any problem any time they’ll send a truck for you?
George’s 1992 Corolla doesn’t even have a MAF . . . it’s a speed-density system
And I think the extent of diagnosis on his car involves retrieving blink codes
Yeah, well, I’m getting a few gray hairs, my memory is a little hazy on which Toyotas used a VAF, MAF, or speed density system. 
But I do have another question for @George_San_Jose1 , when and how did he have the pleasure of working on a fine Citroen?