I'm getting really pissed right about now.....

[chevychic]

My truck is being a PITA again. We had a really good summer, no problems. We went to the mountains, the lakes, and took many long drives together.
Last week I posted about it running rough again on the freeway and was thinking with the colder weather maybe there was some relation. I also thought it might have something to do with the fact I was driving my truck at about 80 mph when normally I stay between 65 and 70. When this happened at the beginning of the year, the problem was suggested, then tracked down to be distributor related. (Even took it to a shop first to have them run a diagnostic on the engine...they suggested the problem was coil related) Replaced the distributor...it ran like a charm.
Now it's doing it again, but with a couple things different. So I'm thinking my problem could have been 2 problems.

Yesterday I had to drive out to another town. After about 20 min on the freeway at my normal 65 mph it starts running really rough. The feeling was like being on a rough road or the tires were unbalanced, lot's of vibration. If I let off the accelerator or didn't try to accelerate more, it wasn't that bad. If I tried to accelerate, it got really bad...lot's of vibration. When I stopped, it idled fine (when this problem arose earlier this year, it would miss badly when it tidled). If I revved the engine, it would sputter a bit as it was revving.
I ended up taking country roads instead of the freeway to get to where I needed to go and home again. It did ok as long as I didn't get on it. But on the way home, about a block or two from my house, I start hearing a whining coming from the engine. As I accelerate it got louder. It almost sounded like the turbo on my husband's GSX but I'm pretty sure no one snuck up and installed a turbo on my truck while I was out
The sound continued after I got home and let it idle. Got out and checked the belts to make sure everything was as it should be and all was good.
Later that night I went out to see if it would make the sound again but it didn't. I didn't try to drive it though.
One thing I did notice when I looked at the engine was a bit of oil that is splattering out over the driverside valve cover. It's coming out of the filler hole and also seems that I need to replace the valve cover gasket. I have no idea if this is related to anything that happened while I was driving but thought it might be worth mentioning.

So, I'm wondering if I have 2 problems.....

Someone mentioned on my post earlier that the rough running could be a problem with fuel delivery. I'm planning on replacing the fuel filter and was wondering if it might be worth replacing the fuel lines as well. They seem kind of old and I figured it wouldn't hurt, but what are your opinions/suggestions?
As far as the carb goes, it's a Q-jet rebuilt last December. It doesn't have the fuel filter in it, in fact I discovered it missing so added one inline between the fuel pump and carb.
Moisture getting into the cap was also suggested but this week has been pretty nice, no rain and not much moisture at night.

The thing that has me confused is why it ran great all summer, taking long trips often at freeway speeds, but now all of a sudden it's running badly. I took a break from doing new things to my engine all summer so there's no way I could've messed something up.

As far as the whine goes....I'm totally lost. I couldn't pinpoint where the sound was coming from and have no way of knowing if the two problems are related.

Help?