major 89 cadi problems tried everything help pls!!!!!!!!!

i own a 89 sadan deville .it started out just running rough out of no where so did a tune up . did nt solve pro. so just kept driving it trying to ignore it .then it started surging real bad when crusing down the road and rough idle . not to long after this started it left my wife broke down on the side of the freeway had car towed to my house . nnext day did a diog. scan with my code reader to see if any codes were stored nothing came up .tried driving a couple times after that got worse now it backfires idles rough as hell spits and sputters just runs out of control crazy. still no check engine light comes on no codes stored dont know how this could be possible car barley runs . i changed map sensor ,cat. converter , mufflers , full tune up ,read the service manual countless times dont know what the hell to do next please help!!!!!!!!!!!!!

thank you
steve

Welcome to AF. Don't take me wrong here but maybe you need professional help with this rather than tossing parts at it. Test the fuel pressure and see what you have post back. Also make sure both injectors in the TB are working.

I had a difficult problem with my old '83 eldo your present situation reminds me of. It was the computer itself. It would not allow the fuel injectors to work properly above idle. I agree also with the other response you have received about a TB (fuel control) issue of some sort. Unforunately I do not know how you test the computer itself for a fault. When my computer failed it did not show any trouble codes. It took me months to figure this out looking down wrong roads(plugged exhaust, etc;) By the time it was figured out I also had to replace the catalytic converter as the fuel problem plugged that up too.
good luck
caddyfreak