My truck misses when it's under load.Have changed plugs and wires. on 2002 Ford Ranger

Does it mostly when under load. Thought about changing Coil now but not sure.

Asked by for the 2002 Ford Ranger
Plugs and wires didn't change it at all? CEL light on? You say it has a misfire under load is it jerking or hesitating?
No lights on. Changing plugs had minor improvement. It Hesitates.
Time to start looking at fuel delivery. Check (have checked) pump pressure fuel trim MAF, o2 readings etc, can try a filter yourself.
You will need to scan the truck maybe drive with scanner and fuel press. gauge hooked up.
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Possible fuel issue.