So among the other annoyances my 92 Ranger has it has a hesitation before it starts spinning the tires under full throttle from a dead stop. It's the 4.0 automatic. I thought it would have more power than it actually does being use to a 2.5 auto. But this 92 4.0 runs and drives good. I've gotten it tuned up with new motorcraft wires, plugs, new coil, fuel filter, fuel pump assembly, fuel pressure regulator, air filter, idle air valve, new O2 sensor, new Dynomax muffler. I can't find any vacuum leaks. The engine idles slightly rough after you start it up from it sitting for a few hours, but quickly smooths out as soon as you start driving it. This one here has no EGR. Transmission feels good, may have even been replaced by previous owner before we got it. It shifts good and the fluid is clean and the transmission is the cleanest part under the whole truck. No way of knowing for sure. The truck currently has 111,000 miles and I did all that stuff when we got it at 101,000 miles. So what could it be? I'm thinking a lazy injector or could it be the catalytic converter? Or could it be the throttle body? I know I once had a BBK throttle body on it and it made the world of difference in off the line power but it kept throwing too rich/lean condition and a TPS code so I had to return it. It sucks because it did help wake up the motor. I returned it and since then the Check Engine Light hasn't come back on.

 

Post up the stft & ltft numbers for both cyl banks.