I currently own a 92 nissan 4x4 pickup. The truck only has 140k miles on it but the fuel mileage has dropped significantly. I've had this truck for 3 years now and it used to get 22mpg but now its down to 14mpg. The spark plugs, rotary button, and distributor are pretty much new replaced last year I think and the air filter is also brand new replaced about 2 weeks ago. The fuel filter is not stopped up, the truck is not out of time, and there is no smoke coming from the exhaust. Any ideas on how to get the mpg back up to where it should be? The truck has a brand new set of 235/75 R15 radials so the tires are not oversized. I haven't been able to check for OBD-1 codes yet because I haven't had a lot of time. Any advice or tips would be helpful, Thanks.

I have also noticed a huge loss in power for some reason..if anybody knows something about that it would be appreciated.

As weird as it sound the KA and SR rely heavily on the water temp sensor. You could start there.

I checked the OBD-1 codes and code 12 and 45 popped up. I cleaned the MAF for code 12 but 45 says I have a fuel injector leak.