Catalac devil ,1990 ,running rough and no power

sounds like it jumped time.

run fault codes to find which sensor is not correct

spark plugs injector cleaner have u been runing with low fuel pump may be on it way try fuel injector cleaner & fill tank 90 plus octane

Do a tune up

1990 Chevy 4.3 l engine runs rough at idle half the time-- sometimes it's OK, other days it's rough and can smell raw gas, as tho it's running rich... any ideas?

Check engine light on? May be air flow sensor.

get a tune up replace plugs and maybe wires. it is not burning the fuel enough which is causing the feul to be rich or lean. try this first.
if car is running rough might be catalac converter. thats where it get expensive.

Junk it *******

On the chevy v6 engines it real comon to have intake leaks.I would try spraing carb cleaner around the intake while the car is running and see if it changes the way it runs.If it does that is your problem.If the intake has a leak it will **** extra air in and cause a missfire.

Check the catalytic converter to see if it is clogged. Also if might be a weak compression.Also you might want to replace the fuel filter