Hey! Ive been struggling with this one.

Just completed an engine rebuild on my 97 Ford Ranger 4.0. Everything works great. Great acceleration. No issues at idle. But whether im driving under load or just sitting there with no load on the engine, when i reach 2500 rpm exactly i get a mild misfire on one of the cylinder. I have yet to figure out which cylinder. It does not misfire below or above 2500 rpm. Ive replaced purge and evap system components for a previous code. Has a brand new cam, fuel injectors and high volume oil pump. New plug wires, plugs and coil pack. Reman'd Heads, rocker arms, lifters pushrods and piston rings are all 2 years old. Compression test is good on all 6.

I first looked into the fuel injectors. Company sent me 5 GB manufacturing injectors and one incorrect one. Was in a time crunch so i ran to pickup one from oriellys and installed it. Stated it was to OEM specs. I know its a different manufactured injectors but would that cause this specific issue?

Looking at a possible crank or cam shaft position sensor wondering if one of them may be faulty at a specific vibration frequency when engine is at 2500 rpm. But wouldnt that effect all cylinders?

Reminder that this wasnt an issue prior to the rebuild. Thats why i want to lean toward injector but im done spending money on this thing. Need help!