hi, this is my first try on the form so hope I;m doing it right.
I recently bought a 84 eldo. cov. after a few weeks started to have trouble, the car shows 91000 mi. don;t know if this is acurate. stated of with engine surging ocasanily shortly after srarted to bog when step on excelarator hard even in park wouldn;t rev up just bog then some time backfire.
what a local shop and I have done so far is check grounds, check fuel presure,cleaned and tightened grounds in dist. checked exhast converter, actualy was bad so eliminated still did it , today was trying to rev. engine it backfired and blew open the muffler, after that it ran better and had more power than at any time I had it , but tonite I stated it and back to same thing drove it about 3mi. tryed rev. it a few times and suddenly stated to run good drove it about10mi all was good, but I never know what to expect when I go to drive it.
ANY HELP WOULD BE VERY MUCH APPRECIATED, I am becoming very frustrated, thanks,. DNE

I always say backfires are caused my ignition problems; especially when it blows up a muffler. I would give it a new cap and rotor and plugs and wires just to rule out that normal stuff. Enjoy.

thanks, will check out youre suggestions,
DNE

I believe Al is correct about ignition causing exhaust backfire. I did have backfire problems with Chevys because of leaned out mixture, caused by vapor-lock, but your Caddy has an electric pump, so the ignition is the suspect..

If the cat. converter was bad, the pieces from the cat. converter will break apart and plug up the muffler as well. So, you would still have a restricted exhaust system. What was the fuel pressure reading? Should be 9 lb minimum to 12 lb max. under all driving conditions not just at idle. If too lean, it will backfire and have poor power. There is a filter mounted on the fuel pump within the fuel tank that, over 25 years can plug up and cause intermittant low fuel pressure.