What now??

[mamato2]

I had custom gauges put in my 83 chevy c10 over the winter. My fuel gauge has never worked right, so i had a new sending unit put in it (still doesn't work, but that's another, non-urgent problem). After the replacement of the sending unit, my truck kept bogging down and dying. Turned out there was excess fuel line, which instead of being in the gas tank had gotten crimped in a "V" shape between the tank and the truck when the tank was replaced. We cut the excess fuel line off and put the tank back up. In the meantime, I also replaced the ignition module. Those are really the only two repairs she has needed this summer til now (wanted to let you know what had been done, in case i screwed something up, causing this new problem). The truck had started to run rough, in idle or during driving - kind of hesitating, lacking some power and backfiring. But only sporadically - sometimes it would do it and other times it was fine. I bought fuel system cleaner and dry gas in case anything had gotten into the tank when it was dropped. After i put that in it, it ran fine for 3 days, but has since started again and the truck is really sluggish now. I checked the fuel and air filters, which are fine, the fuel pump is new and i had a brand new edelbrock put in it over the winter. I checked for a vacuum leak, but that seems fine too. I don't know where to look next. It reeks of gas, but always has and my mileage sucks (averaging 6 or 7 miles a gallon). Also, as i was driving it to work last night, 3 times i heard a loud knock under the truck - i know it wasn't a backfire - it was extremely loud, seemed like it came from the drivers side. Almost sounds like a hammer strike against something solid - like the wood in the bed or a solid steel component. Scared the crap outta me. When i turned into the parking lot at work (there is a big speedbump there), the truck sounded like it made a cracking/grinding noise as she went over the bump. I am not sure what could be causing this either. Ughh.... Well, this is a long post - thank you for taking the time to read it. Any advice or thoughts on what to do next would be greatly appreciated!! Thank you.