I have a 99 E-250 with the 4.2 six ( with 150,000 miles) and 4spd auto. When the weather is cooler (under 60 degrees) the truck has all kinds of power and mileage is around 14.5 hwy (truck does weigh 5300 lbs empty). When it warms up (over 60 degrees) the truck doesn't have any power and is a struggle to hit 65 mph. Mileage drops to around 13.2 also. It feels like I'm pulling a heavy trailer when the weather is warm. When it's cool, feels like I have the V-10 under the hood. It's a Jekyl-Hyde thing (maybe more Heckle and Jeckle?). I'm running a K&N filter but it hasn't changed how the truck runs. What obvious things should I look for? Thanks for any help!
- posted
20 years ago