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1991 Deville 4.9 rough idle very poor acceleration

Old 03-29-2012, 08:12 PM
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Default 1991 Deville 4.9 rough idle very poor acceleration

Hey everyone, I'm pretty new to the forums. As a mater of fact this is my first post. The reason I've come here is I'm having some major problems with my in-laws 1991 Deville. So let me start by giving you some history on the cars recent problems. My father in-law was leaving for work on monday morning in the cadillac. He pulled out of the driveway, and went down our street with no problem. When he turned on to the major road the car started sputtering and had hardly any power, he was just able to coast it into a close by parking lot. A little bit later I went to pick up the car to see what was wrong with it. At that time I was hardly able to get it to start, the breaks felt rock hard as if it had lost power break boost. The only way I was able to get it home was to keep one foot on the gas and stand on the break with my other foot.

After I got the car home I did a little research, and found some posts that pointed me in the direction of replacing the break booster and the problem would be solved. Doing this did solve the rock hard pedal issue, but the car still idled very rough, and has hardly any power. After finding out how to check the on board codes I found I had a code that lead me to some information telling me I had to replace the distributor. I went to the junkyard, and got a "new" distributor, and put it in. I can now get the car to idle, although its still very rough to me.

So as this point the car still idles very rough and has next to no acceleration. On top of that when I rev the engine up a little bit in park the transmission seems to make a click sound when it comes back down. The click is sometimes paired with the vehicle learching forward.

Any help would be great. This thing has been wearing me out (anyone that has changed a booster on one of these could attest to that).
Old 03-29-2012, 08:45 PM
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I forgot to post that I have check the fuel pressure at the rail and it reads between 38-42 psi. The on board diagnostics are clear at this moment as well.
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