I have a 2002 ford explorer. Cylinders 3 and 4 are misfiring. I have already replaced the spark plugs and wires, but it cotinues to misfire. When I start to accelerate the engin bogs down and at 40 - 50 mph it does the same. please help

 

This may not be the problem, but did you change the fuel filter with the tune up. Plus are all the wires located on the correct cylinders to coil. On my 2002 Ford Explore I had to go to Ford for the filter and it cost up to 32 Plus dollars. The WIX filter at the local parts store did not fit on the side that went to the filter to the engine.

Good luck