Rough run and idle plus code 21 (1 Viewer)

[Bigmeanred]

This has been happening for just over 6 months now. idle throw something at it and it would fix it for a a short time and then go back to running and idleing like s***. I've replaced spark plugs, leads,rotor button, distributor cap, (tried to put a new distributor in but came up with a code for rpm so put the old one back in). Coil, igniter, fuel pressure regulator (after doing this i got a 2 months of just poor cold run and idel till it got up to operating temp and some time a bit of struggleto start when hot), fuel pump, and just replaced the o2 sensor and still have a code for the o2 (i only have 1 and its before the mid muffleri dont have a cat with the new systemi put on a few weeks ago and the old one didnt have one either). Makes no difference to how it runs and idle with it plugged in or unplugged. Yesterday when I put it in ran ok above 1200rpm but under it would struggle while driving but now it won't idle or run right (like it's only firing on 5 out of 6 cylinders the hole wagon vibrates). I did some testing yesterday and all 4 cables from the ecu to o2 are good and no shorting between each other just took voltage at 2500rpm 1 has 0v 3 have 1.1v. Ecu has a good earth. I'm ruling out vacuum leak as I just sprayed every vacuum line in the engine bay with break clean and it didn't pick up. Also now idling down at 450rpm not 650 like it was and when I first got the wagon when the ac compressor kicked in it would jump straight up to 1200rpm now it takes for ever to just get to 1000rpm if it even gets there. As I said everytime I replaced something it helped but not for to long I'm running out of ideas. Thanks

 

[Bigmeanred]

Sorry edit it is a 1994 1fzfe