I own 3 Nissan trucks and 1 GMC. I own a Thunderbird and a Pontiac. I don't own the Nissans because I think they are the best trucks in the world. But because I have pulled the engine out of one so many times I could almost do it in my sleep. I know them.. But this Thunderbird, Although its not a truck, I hope I can find a little help on it. Its a 93 T-bird with a 5.0 HO. And its dead on every cylinder on the drivers side bank. Compression runs low on all 4 of those cylinders. And the intake (Fuel Injected ) is stopped up where the PCV valve plugs up. The computer is fireing the injectors and the plugs are all firing. I removed the intake plenum and can't see that it is or the intake is stopped up there. The engine does not knock but there does seem to be a good deal of blow-by.. What would take out all the cylinders on a bank at once ? BTW, I bought this car in this condition. There seems to be about 4 or 5 quarts to much oil in it so the blow-by could be a result of that. I have tried and tried to come up with some idea but my mind starts to draw a blank past the valve train being down on that side.. Maybe it stopped oiling and wore out the lifters ? ( I'm told that this thing has both a roller cam and roller rockers ) My wife fell in love with this thing at first glance. The body is great but it could use a new paint job and some work on the insides. Help me if you can. I will pull and build the engine if need be but I'd rather find what and why so I can make sure it don't happen again.. Thanks in advance for any help.