Caprice miss and/or fuel problem

[90capricewagon]

Hi everyone, new to the forum and could use a little help on this problem. Here are the details.

1990 Caprice Wagon with the 307 Olds motor. I am having a problem with it missing and lack of power "kind of sputters and doesnt seem to want to go". I have put it on an engine analyzer and all the cylinders seem to be firing ok. I did a cyl balance test and i have about half of the cylinders dropping around 10% and the rest except for cylinder one are dropping in the range of 5-6%. Cylinder one was giving me some intermittant readings of -1 to about .9%. I have removed the cap and rotor and cleaned them up. They looked good other than a little carbon buildup. No burn through and I could not find any cracks in the cap. Also for the moment I have completely removed the fuel filter and air filter which did no good. I also found a vacuum leak on the top end and fixed that which also made no change. I have looked it over and cannot seem to find any other obvious problems. Set the timing to 20 degrees BTDC as posted on the emissions label. However I am not sure if I did it correctly. I unplugged one of the harnesses under the passenger side dash which changed the timing so I am assuming I did the right one. I cannot seem to find the infamous single wire connector that I am used to with the orange wire. Please help. I am at a loss on this one.

Also It will miss at idle and at highway speeds if that makes any difference. And the cat has had its guts removed. I plan on getting another one tomorrow. I am doubtful that this will cause the problem though.

I am pretty new to this type of mechanic work so take it easy on me.

[silicon212]

Are you getting any type of valvetrain clatter, such as a rhythmic tapping/ticking/smacking sound from the top end of the engine? If so, you either have a sticking/collapsed lifter or a worn cam lobe. Unlike a Chevrolet engine, the valves on your engine cannot be adjusted, so if there's wear to the valvetrain, you'll have to replace components. You said you ran a balance test, which is good, but have you run a compression check? You ideally want all cylinders to be within about 2-3% of each other. If there's any significant variance, this might denote a warped head and/or blown head gasket. It could also signify burnt valves which will cause the condition you are having. So will bad vacuum lines, so make sure they're all replaced.

[90capricewagon]

Thanks for the reply. No there is no valve tapping or clicking...at least not that I can hear. Unfortunately I did not run a compression test. I also have not double checked all of the vacuum lines. They all look pretty old though so I should probably change them. Not to sound ignorant, but could this be a fuel problem...junk in the tank, fuel pump dying, etc?

I did forget to mention that this is not a problem "all" of the time but "most" of the time. In other words I drove for about 30 miles home and it did it probably 2/3 of the time. However the entire week before this it had been doing really well and only did it a couple of times for just a few seconds.

Thank you again for the help. I will get back on it tomorrow...again