Rough Idle and low economy

[HarleyRider]

Hi guys. Just fixed a fuel leak (replaced the fuel pump behind the fuel filter canister) on my '97 F350 with a 7.3l psd, but have also noticed a rough idle while stopped at red lights, stop signs or just idling in traffic in Dallas. The fuel economy has also taken a nose dive over the course of the last two years (from 16-17 mpg down to 10-12 mpg). The only mod on this truck is the K&N air filter. The fuel in the filter bowl is clean and clear and the fuel filter is clean (no oil). Brother in law is a gas engine mechanic but he plugged into the data port with his new scanner and got no codes. The scanner did the contrib. test and the only cylinder that had the least rpm change was #4. He researched All Data on their shop computer and the information there suggests injector seals. How difficult is this little job? I bought the seal kits from the local Ford dealership and felt like I was getting robbed, but maybe not if it fixes the problem and I can do it myself. The truck has 180k miles on it and I've been driving it for 10 years. The tranny was overhauled at 101k, water pump and glow plugs a short time after that, and the fuel pump last weekend, so it hasn't been a problem truck.

Any advice would be appreciated.

Thanks,
Dale

[SMKSTAX]

1st off WELCOME TO THE ORG!! Someone more knowledgable will be along to help ya out.

[HarleyRider]

Well, I took the truck to the shop and the tech found that the # 8 injector had not totally failed but was not operating as it was supposed to. It wasn't setting any codes and nothing would show up on his scanner. I had him replace it and the truck now runs like it did when I bought it.