ok guys I need help, I have a 2000 ranger that is miss firing on cylinder 3, and 4. I changed the plugs, wires, and ignition coils, no help. I changed the timing belt no help. Checked the compresson on the cyllinders and 3, and 4 are both lower than 1, and 2. Any ideas, the truck has 188,000 miles.

 

What is the compression across the cylinders like the the numbers? is the spark to 3 and 4 strong like 1 and 2 or weaker?