Why does my Nissan Altima/Bluebird 1994 jerk whilst driving/stopped?

Hi,

I have an automatic 1994 Nissan Bluebird which I think is equivalent to the Nissan Altima in the US.

My car seems to jerk whilst driving, not specifically under load.Sometimes when I’m in park with my foot on the brake, it feels like its very subtly jerking on the spot. It is a sporadic condition, sometimes my car won’t jerk at all (or very few times) on the way to work, and other days it will jerk a lot. On the whole it seems to be getting worse though. When switching between gears when stopped it changes quite roughly (but not violently). Turning on the AC makes the condition worse. It has stalled once in reverse, and sometimes feels like it will stall again when I’m slowing down.

When it does jerk I can hear a noise that sounds faintly like a can of coke being opened (quick sharp pressure release), and it seems like something (possibly a belt) is losing traction/slipping and quickly regaining its grip.

My first suspicion was the drive belt or one of the other belts slipping or something like that. Other possibilities I suspect are, from looking through the Hayne’s manual:

-Something to do with the transmission (I checked the transmission fluid and it seems fine, very light brown but mostly transparent)
-Fuel filter clogged or fuel line problems (1.5 years ago the car wouldn’t start, and a mechanic had to manually inject fuel through the injection nozzles. The fuel was near empty however)
-Spark plugs gap wrong or damaged
-Distributor components damaged (the distributor and alternator were changed last year and swapped in with 2nd hand parts, also the mechanic was very shifty and I think he hacked it into my car without too much care for good wiring, fittings, etc).

I would greatly appreciate suggestions on diagnosing the problem. I am keen to learn more about cars, though unfortunately I have limited equipment.

Also, I took the car to a mechanic last week and he thought it was the spark plugs, but I think the problem may be more serious than that. He also wanted to flush the transmission fluid but I think I will give this a miss since I checked the fluid and it seems fine, plus I heard flushing the fluid in an old car may have negative effects.

Thankyou!

With a 20 year old car there could be (and likely are) a multitude of issues to deal with, but the first parts that I would check are the motor mounts.