You mention bucking. Would the term 'bogging' be useful? I'll let you look that up with regard to describing auto engine and acceleration performance.

Bogging may be attributed to a failing throttle position switch (and other items) and these can be well along in failing before the ECU sets a fault code for you to check using the OBD.

Have you inspected the electrical system? The well-lamented engine control system 25-AMP fuse and fuse holder on the inner fender behind the battery. Corrosion. Zen Master Uncle Arty B. treats the topic well.

http://cleanflametrap.com/emfuse.html

Also, in the fuse box, try the "spinning the fuses" trick to dislodge corrosion between the fuse end and the fuse holder clip. Also, give a close inspection to the fuses. Also excellently treated on the aforementioned cleanflametrap.com page.

Though, for a lark, before you futz with power and ground issues, have you checked the engine control system for fault codes using the OBD fault checker box?



https://www.brickboard.com/FAQ/700-900/EngineOBDCodes.htm

Specifically, for the Bosch LH-Jetronic 2.4 / 3.1 fuel injection and emissions (socket 2) and the Bosch EZK 116 ignition and emissions (socket 6). Repeat the procedure until no new fault codes display. Though not all items that may have a fault will be so faulty as to broach the threshold for the engine control units (ECUs) to set a fault.

Else, a timing belt so in need of tension-reset it may have slipped a tooth on one of the timing gears. Doubtful.

Then check the 25-AMP fuse holder. Give a wiggle to all connections along the watchtower, oop, I mean the engine control wire harness connectors in the engine bay. Such as the connector at the ignition power stage. Disconnect, inspect, replace. (DeoxIT would be great if you have any of the ointment or spray. Don't lose the connector seal!)

May want to test the AMM for fault by unplugging it and seeing if the engine runs better, if rich, yet 'better'. Any exhaust leaks upstream of the 02 sensor?

Hope that speculative helps.

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