1993 3.0l

Have a 1993 3.0L Sundance Duster. Posted on this forum as I believe Acclaim and Duster shared the 3.0L. Engine will hesitate/buck while underway and sometimes die at idle. When engine stalls at idle, many times the RPMS will
jump up and engine will remain running. Plugs, wires, cap, & rotor were overdue so I changed those. The ignition timing seems to wander, when I
unplugged the coolant temp sensor timing appeared more stable so I replaced temp sensor without any improvement. Pulled a code 21 from the CEL, related to oxygen sensor, will replace that tomorrow. Anybody have any
tips or thoughts? Thanks. Car has 130K. Fuel tank, fuel pump, fuel sender, and fuel filter were replaced about 1.5 yr ago.

Replaced the O2 sensor, could 21 did not return, but vehicle behavior did not improve. Has anybody
had problems with the auto shutdown relay or camshaft position sensor in the distributor?

Car finally acted up enough to set another code. This time car stalled in driveway and would not restart initially. Retrieved a code 11 - no signal from distributor. Purchased a remanufactured distributor from Autozone for $128.00. New "ignition module" alone would have been $122.00. Was disappointed after bringing reman unit home and opening top cover, electronics appeared used. Anyway installed reman unit, set timing, and problem appears to be solved. While researching problem found that if computer senses no signal from distributor the autoshutdown relay will deenergize fuel pump.:)