Goes up to 25 mph, no faster

[TWH]

(Posted in electrical, too)
I have an 89 Ranger, 2wd, auto, A4LD. Been sitting idle for several years and I just can't seem to make it stay running. I got a reader and it coded out with a code 53 "throttle positioning sensor above max voltage," and a code 89 "AXOD Lock-Up Solenoid (LUS) circuit failure or Clutch Converter Override (CCO) failure." I noticed that the front bumper was bent, so I made sure the fuel cutoff (kill switch) was reset. I can get it up to 14 mph, runs great, shifts into 2nd and starts to surge. Keeps on surging till I let off the gas just a little bit and then runs great up to 25 mph. Starts to surge again and then won't go over 25 mph. On 2 separate test drives the surging just went away for no apparent reason, ran great. Stopped, started, took off fast, took off slow. It did great, but as soon as I put it back in park and drove it the next time the surging started all over again. It idles fine, BTW.

Partial list of new parts: Fuel pump, alternator, fuel filter, tank has been flushed out, ignition switch, steering column switch (slider), throttle positioning sensor, but it has not been set by a computer.

Before I was given the vehicle, it sat on the tarmac at the airport with a blown tranny for about 2 years. Transmission has been replaced by another mechanic. Numerous mechanics could never get vehicle to stay running. They all worked out on the tarmac on the vehicle over a period of 3 years on and off, with no special tools that I could tell. They all threw in many parts (i.e. rebuilt computer, mass airflow, sensor, throttle position sensor, one coil pack, maybe more?) just trying to get it to run.

HELP!! What should I try next?

 

[Dave R]

The TPS is a problem but it would not cause the troubles that your having. Generally speaking, a failure to accelerate beyond a fairly low speed is caused by either a lack of fuel or the spark ignition timing not advancing.

To that end,

Have you checked the actual fuel pressure at the rail?

Have you checked to see if the static timing is accurate and the ignition is advancing? Have you checked to make sure that the timing belt hasn't jumped a tooth or two?Another posibility is a failing ignition module.

Unless your in California that truck shouldn't be Mass Air.