I hate to keep beating a dead horse but after searching this topic it's not getting much if any responses. I have a 1994 Ranger 4.0 auto. After warm up 6-8 seconds it starts to hunt to a rough idle. I can live with that right now considering it's got 171K.

My biggest problem is it has a mind of it's own. Some days runs good but some not, very erratic. If I baby throttle, it runs without bogging. If I accelerate harder it bogs as if running out of fuel. Once I let up it immediately will accelerate to run slow but will repeat the bogging cycle if I accelerate harder. Starts fine, no black smoke. Mileage is bad. Fuel pressure good.

Brief history. I received it from my dad who bought it new & always kept good care of it. He no longer sees very well so I want to keep the truck mainly because it's his & I like it.

What I have done mainly because of various codes , recommendations from friends, & routine maintenance.
Fuel filter
Air filter
Battery
Spark plugs & wires
Coil pack
MAF sensor
IAC valve
TPS
Both oxygen sensors
Fuel pump
PCV valve
Fuel pump relay
Jumped the Inertia switch

My thoughts are the Fuel pressure regulator valve. I pulled the vacuum hose off but no indications of fuel leakage. Can these be dry & still be bad? Thanks for any info.

When it bogs, does it feel/sound like a fuel issue or a ignition timing issue?

What codes have you pulled since this started?

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