This may be a long shot, then again maybe not, but some of the items suggest a catalytic converter restriction. The "quiet" engine is one of them, and loss of power while running somewhat decent also suggests it. You might listen at the tail pipe for normal (or abnormal) exhaust note or output.
Automobile(s): Cadillac 78 Seville, 78 Coupe de Ville, 92 Sedan de Ville
Re: lost of power
I think that's a good call steelybill, after reading through the thread again it does sound like a clogged catalytic. It's quieter than normal, takes more pedal pressure to get up to speed, lousy mileage, check the vacuum with a vacuum gauge. If the cat is clogged the vacuum should be way down.
Automobile(s): 1993 Cadillac deville sedan 1986 cadillac deville RIP
Re: lost of power
It might because I have to give more effort than usual Togo up hills and drive ways .the lowest voltage ive seen is 13.6 . When I took it to the shop they replaced my egr and 3wks later the shop cleaned the carbon build up and in a couple weeks voltage is down and steering stiffness and lost of power
Voltage is NOT down. Forget about voltage, you dont have a charging problem. 13.6v is fine and dandy. When the alt is cold it puts out more voltage which is totally normal.
I agree that the converter is worth looking into. A crude way of checking it is to remove the o2 sensors and see if your problem improves. The holes in the pipes where the sensors were will release the back pressure.
It's also possible that the ISC motor has died and is not keeping the idle up where it should be but it will not affect your gas mileage because that part only influences the engine at idle and coastdown.
I believe the 02 sensor is in the rear manifold, (just ahead of the firewall) and kind of tough to get at on a FWD (mine was). Did you listen at the tail pipe ? If the cat is plugged, just a whisper of exhaust and noise will be coming out there.
You may have to have a muffler shop look at it if you don't have the tools to deal with exhaust systems.
The vacuum gauge test will also tell.