98 Ranger
5-Speed
2.5 L 4-cylinder (8 plugs)
135,000 miles

My 98 Ranger Daily Driver hesitates severely when accelerating. Going up a bridge is a challenge. It mainly occurs when giving more than 15% of the throttle. However, it does not occur at all times, every once in a while it drives perfectly.

There is no check engine light on nor codes (according to AZ). I am on my third set of plugs and wires. I changed the MAF sensor in 2001, and put accel coil packs on in 2005. The latest set of plugs/wires were installed 6 months (10K MI) before the problem occurred. I have since changed the fuel filter again and fuel pump, but the problem is still there.

There was a TSB regarding wire chaffing on the drivers-side of the under carriage, but there was no wiring harness an my truck in that location.

In the past the CEL light would turn on, and then turn off after running another tank of gas. This would occur once or twice a year, for at least a couple of years. It was an EGR code. I replaced the EGR valve even know the CEL has not been on in several months.

There is a rattle coming from the floor board when accelerating in 5th gear at hwy speeds, but the rattle has been there for several years. Could this be a cat problem?

Would a faulty MAF sensor always throw a code (like the first time I changed it in 2001)?

Any Ideas on what the problem could be?

Thanks in advance!