Thanks Bob,
I found the block and checked the lines. All appear to be fine. The problem doesn't exist until the throttle is pressed fairly hard, but it seems to get worse as the car warms up. I suspect a crack some where heat can be causing a problem so I doubt it is the plastic block. Still, I'll pull it out and check it. I checked the rubber tubing going to the valve cover and that area seems to be okay too. The block only had one in and three out. I did find that one line was completely disconnected, but after connecting it there was no difference. I have another issue in that the AC works very well when the car is first started, but as it warms up the AC air gets warmer. Not to the point where there is no AC but noticeably warmer. Don't know if the two problems are related or not.
Pete