Trying not to bore you with too many details, but don't want to leave out anything important. Thanks for taking the time to read:
1985 GS. Last month, I had sporatic stalling which would resolve itself when the car cooled for about 20 minutes, I started to notice noise from the fuel pump and then one day it would not start, so I changed the fuel pump. Along with it, I changed the fuel filter. At that same time, only because it had been a few years, I also changed the distributor cap, rotor, spark plugs, wires, and air filter. The car was running beautifully.
Last night, while driving up a very steep hill, out of nowhere, the engine became sluggish and then stalled. It kept stalling under load, but would start easily and idle fine. Using gravity, I turned the car around and drove down the hill and took an alternate route home along a slower incline. I got almost all the way, but the last hill was too steep.
Today, it still starts and idles well, but when I rev it too high (like 5k) it will stall - but restart immediately. In gear, it will barely drive, but if I play with the clutch and gas, I can keep it moving as long as it's not too steep an incline.
I made this 1 minute video clip:
https://youtu.be/rdypw752aCs.
This happens to be my daily commuter, and it has not been sitting. So, I would like to rule out clogged carburetor and rust in the tank, especially since the problem came on suddenly. I introduced into the tank a bottle of the most expensive gasoline additive/cleaner I could find in my local parts store and I used (followed the instructions carefully) an aerosol carburetor cleaner. After the treatment, I left the car idling for 20 minutes. Came back, no improvement.
All four plugs are getting a good spark. I removed one at a time from the cap and the arc is strong.
Thoughts? What else should I check/change? The fuel pump I bought is an ac delco EP42S. There were more expensive pumps available, could this pump be the problem?
Thank you. Pete