I have a 1990 Mazda B2200 with a standard 5 speed transmission and a carburated,4 cylinder engine.It seems to run better at different times,but has a,"what seems to be",
Jerky,loss of power at other times! Any input on what may be causing this,would be great! Thank You!!

. Replace the Ignition Control Module (ICM) and coil.

. Change the spark plugs with the same ones that came in the truck, if they have not been changed in the last 3 years.

I suspect the ICM (AutoZone JA143, $72.99, 2.2L Engine) is failing and the main culprit.