MY 1989 Buick lesabre is starting to lose power, especially going up hill, I need help please

You should have a wiper fuse in the interior fuse box that you can pull to temporarily turn the wipers off. I suspect that the issue is due to a bad wiper switch which will need to be replaced.

There is no code 8 , codes start at 13
>

If the engine is idling smoothly and starting easily, I would suspect a transmission issue.

Not anymore it isn't a nice car
Sounds like oil & coolant come out
into the coolant recovery bottle
You lost a head gasket or thermostat
stuck closed
I think it's time after 24 years to send it
to car heaven & take the tax write off

u need a fuel filter posibly a fuel pump. start small then go big. could also be your egr valve.

check the ground wire blk/brown

Sounds like the throttle body is sticking. Do not use WD40 to free it. Use some Carb cleaner on it and then oil it with some synthetic 5w30 engine oil. You may also have to clean the MAF and MAP sensors if this is fuel injected. I had a 2000 Buick Lesabre and the glue came off letting in water when driven in the rain. It would cut out till the heat from the engine dried out the water and then it would work again.

Buick 3.8's are notorious for intake manifold leaks. If you are sure you are not leaking externally (look under the alternator and on the top of the transmission), it could be an intake manifold leak. I've replaced mine...I didn't think it was too hard a job for an amateur.
It could also be a head gasket, but the intake leaks are much more common.

Sounds like what is called shutter changing to synthetic fluid fixed my 98 Lesabre

It could be the fuel filter. Check fuel pressure and volume.