This is a CIS KE jet car correct? There should be a procedure somewhere to measure the duty cycle / voltage at the . . thingy on the fuel distributor that alters fuel mixture.

This will give you some sense if the computer is trying to lean out fuel mixture but is at the limit or the computer is forcing things rich.

Has the manual mixture screw been turned at some point in the past? You can get some sense if the mix is too lean by pushing down on the adjuster extension until it engages the real adjuster then pushing a bit farther and seeing if the motor smoothes out. While the adjuster extension is engaged let the adjuster come back up to center, rotate it just enough to grab the real adjuster then pickup, if the motor smoothes out the mix it too rich.