Gas Mileage Issues

I have posted a thread previously and since have actually had a decrease in gas mileage. I am only getting about 9 miles per gallon. To better inform you I have a 98 Dodge Ram 1500 with 2wd and a 5.3L. It has 88,000 miles. Is this gas mpg normal? I have checked the intake, changed the sparkplugs and wires, all fluids synthetic, fresh oil, and proper tire pressure. My truck seems to be running rich, and almost seems to struggle alittle upon acceleration.This is the first Dodge I have owned and purchased it from an older man (showroom new), When I purchased this truck it came with a K and N air filter. I removed this upon talking to a Dodge mechanic who informed me sometimes how a K and N filter will trick the computer and make the truck run on how he explained basically as choke mode. It helped for a little while but its back to normal. This gas mileage is 9 mpg in all conditions, pulling my trailer, wide open, city, and highway. Please Help!! In addition, I also had the computer codes checked and they all came back perfect. :banghead:

yep, i have some advice for you. it's a pain to do, but, my buddy has a 99 ram, and i have a 96. i have yet to do it, because i haven't had problems that have been affected by this. but, if you read up on it, you will notice that alot of dodge trucks have problems with the pleanum gasket. it takes a while to get everything off and get into it, but if you decide you want your truck to run better, including not rich, and increasing gas mileage. then i'd suggest changing it. and. also. if you have a little extra money, i'd suggest investing in the aluminum pleanum. it is alot less likely to ruin the gasket. but the pleanum gasket is located under the intake manifold. you'll see oil inside it and around it. it covers up the valve body. and you'll have to remove the entire throttle body. as previously stated, it is a pain. but it is so worth it. try it and let me know what you find out