re: when typing I put 1988 in discussion about hard starting when it should be 1998,and I never heard of a one day valve but chilton refers to it in there manual for this truck.
Maybe they’re talking about the valve’s lifespan. lol
I also had a Dodge RAM of that year, and this has throttle-body injection. I still think you may have a leaky fuel injector, and this will cause your mileage to drop as well. Not that it’s easy to tell with one of these vehicles. I used to pretty consistently get 11-13 MPG on my 4x4 with a 5.9L. BTW, it looks like you started a second topic for this added comment. You should add comments to your original post.