I got an 85 GSL 12a, with 130 k miles. The car has been running well and I notice a loss in power four days after a radiator flush and air filter clean up. The engine is running good but feels like its being held back. I notice it the most when going up hill, could anyone help me with what could be wrong?

 

you could have a vaccum leak. make sure that you have everything sealed and all hoses connected(especially the hoses by your carb, unless you have a fuel injected system).

 

few things I would check ... most likely fuel filter ... have that checked out ... other things would be catalytic converter (after doing arun and you start feeling it loosing power as you say, stop the car but keep it running and look under the car see if the cats are glowing red) that would mean the catalytic converters are clogged.

 

Totally check your fuel filter. I had the same problem, 1985 12A with 145k and I had a major power loss going up hills and prolonged high RPM's. Changed a $5 fuel filter and it solved the problem. It takes 10 min and super easy to work on. I thought it was more complicate than that, but start there. It could save you a lot of time and money. Good Luck

 

I agree ith Dj55 as for checking the cats. If you have any.
It helsp outt he forum when you aska question to completely describe the setup on your car.
Are you still running the stock carb? Is the exhaust stock?
The more info you pos the better chance you have of finding an answer.
I've had customers bring me their FB's in the same situation and find out the fuel pressure was too low. Old fuel pump, nothing more.
You could also check the small screens in the carb where the fuel line connects(if you are still running a stock nikki) for any build up. This would inhibit fuel flow also.

Good luck.
Keep us posted.