Caprice miss and/or fuel problem

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. :banghead:

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.

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