02 Venture running rough under load

Good morning. I have an 02 Venture WB Package with the 3400 engine. Within the last week is has started to run rough under load. This happens mainly when it is driving, but it does happen at idle when there is an incline or decline.

A little background of what happened. It has not wanted to start all of the time and i heard that it might be a dirty MAF. Well, the MAF is clean and still not wanted to start all or the time. During this time I noticed a plastic line going from the intake tube into the rear valve cover was loose, so I thought this was the problem. I have big hands and couldn't reach the rear vavle cover without rocking the engine forward. When I finally got the bolts out of the mounts that attache to the engine, the engine rocked back a little. I didn't think anything of this and ratchet strapped the engine forward so i could reach the valve cover. I got the line back in and put the engine back where it is supposed to go and all was well. A few days after doing this my wife told me the van was running rough so i took it for a spin and she was correct. It is hard to describe the sound it makes, but it almost sounds like there is was too much stress on the engine when I have the gas peddle pressed. The van doesn't lose any power i don't think. The van sounds great if it is coasting.

It only does this when there is a load on the engine in drive or if it is idle or parked on an incline or decline. It goes into the shop on thursday the 30th, but I would rather not spend the cash if i can do it myself. I am totally lost with this one. I have a video of the sound when I am driving it, but the sound isn't too lound on the vid.

Has anybody had this trouble before? Please help!!

Thanks

http://i1192.photobucket.com/albums/aa332/Koscoe/th_DSCF1017.jpg (http://s1192.photobucket.com/albums/aa332/Koscoe/?action=view&current=DSCF1017.mp4)

Does it have a misfire? For example, cruising up a slight incline on the highway at 50-55.....now slowly accelerate......does it start to misfire?

Has it been scanned for misfire codes, like a P0300?

It doesn't misfire. I had it scanned at a local auto parts store and no codes. My mechanic can't scan it until thursday. I wish it was throwing a code.

I finally got to drive it when it was quiet out and heard a noise when I let off of the gas. It sounded like a small BOV for a turbo. Do I have a vac leak somewhere? If I do have a vac leak, wouldn't that make the van run rough all of the time no matter of the conditions?

Mechanic said it was a clogged cat, so I had it replaced and still did not fix the issue. Now they are saying it might be the muffler. I think they are chasing nothing, but I will have it looked at. They seem to think the exhaust is plugged. I am not a mechanic so I don't know.

That mechanic was way off of the mark. I took it to another mechanic and they had the problem found and fixed in half a day. A motor mount had gone bad. Now it runs like a dream.