Hi Rapid Robert. Well, I changed the temp sender unit today and walla, the gauge works just perfect. You gave me the info I needed to start tracing the problem and I found it. Seems it was likely that the new sender I put in was for idiot light dashes and not gauge. First I heard of that but it worked when I got the right one.
I have boiled it down to the tank sender unit as being the problem with the fuel gauge. Even though I tested it when I installed a new tank, does not mean I did it right. So picked up a new sender today and hopefully get it in tomorrow. Damn and there is gas in the tank too. I am going to test the new one hooked to the gauge before removing the tank. LOL. Thanks a big bunch so far and will keep you posted.