HELP: Can anybody help me diagnose this problem I have a 400 in my 1976 cougar with a new carburetor new distributor cap wire plugs rotor coil starter selenoid brake master cylinder. As of two nights ago I parked it running fine and went to drive it The next morning and it had these issues.. It was only idling at 2-300rpm, it stalled on me so I turned the idle screw all the way in and it's still only running at 500rpm's?it's very rough and has quite a bit of backfire, it's overheating, hesitates a little on the gas, and for some reason the brakes become very stiff and weak when I'm moving slow like trying to park or something? I don't know or understand how all these issues can come up at once please if anybody knows what is causing this let me know!
My car has 9000 miles.
My car has an automatic transmission.
My first thought is you have moisture inside your distributor cap. This is a very common issue with older vehicles. I suspect all these issues are caused by a single issue. Since it is overheating, I would certainly be checking your cooling system. I wouldn't expect it to blow a head gasket, but your symptoms definitely fit. It could also be clogged carburetor jets.
With an overheating car, I would begin by determining which cylinder are misfiring. If cylinders are misfiring on only one head, I would suspect you have a head gasket failure. Whatever is overheating needs to be addressed. It is very difficult to diagnose a car when it is overheating.
Another possibility is the roll pin holding the gear on the distributor has sheared. This can cause overheating and all of your symptoms. I think I would begin by checking your timing. If it is way off, I would suspect this. While your there, inspect the distributor cap for moisture.
If you should need further assistance, have a certified technician, like one from YourMechanic, diagnose your misfire firsthand for an accurate repair.
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