Joe,
The car has had this problem since I bought it. I have been working on other things that I'm more familiar with ie. paint, body work, replacing interior, etc.
I just did a complete fluid fluid change on it following your directions previously posted. I tightened the valve bolts while I had the filter off, but it didn't help the problem. Fluid level is correct. I assumed that the diaphragm would be ok since it isn't smoking at all. Is it still possible to have a diaphragm problem without the obvious white smoke? I just got a new timing light and plan to check the timing tomorrow. I'll post back the results from that. I know I saw a post (yours I think) that shows the input on the transmission for a gauge but for the life of me I can't find it again. I need to start bookmarking these when I find them. It gave me hope that the transmission may not be a complete loss when i moved the lever and got a good response from shifting. I am hesitant to move that rod without a gauge present to tell me where I am as far as pressure. I don't think I have a vacuum leak and until now I thought that vacuum was only a factor when at idling or low speed. This is where my lack of knowledge is failing me. Thank you for helping.