Hi, I have had a 90 Eldorado with the 4.5 for close to a year. The car has 82,000 miles on it and has always run smooth. One day it started running rough
& then subsided & ran smooth again. Not much time went by & it the started running very rough again so I took it to a mechanic so he could maybe give it a tune up & make it run great again. The mechanic said the #5 cylinder is dead, but he was not certain why. Maybe a bad valve he said. Does any body have incite to this particular issue. He said it would be $700.00 to $800.00 to do the one head. Any help is appreciated. Thanks.
He did not explain that & I did not ask. He did say that the existing plug was not firing. He replace it & said it is firing now & I remember him saying it is getting fuel so that leaves the compression in your three choices given.