Sorry to hear this Cruiser....That's your pressure test,what about the cyl compression test? You need to find out if all 8 cyls are compressing uniformly or at least within acceptable specs...you may uncover the location of your issue right there. If not then go to the block leak test,or bring it to someone that can do it for you. Any time I run into issues like this I start with a compression test.It gives you information on the engines general conditon,operating and mechanical. Usually turns out to be the most important test of all.....