I am having some persistent problems with my car, mostly with the transmission itself and the others i think are related to the transmission. Apologies for the long post but I don’t want to leave out any information that may be pertinent to the situation.

Aproximately 5000k ago I had a full rebuild done on my gearbox in my 95 EF falcon. All went well for about 4000k and then the gremlins appeared.

1st The car had to be put in neutral to start once (neutral safety switch playing up – no drama)

2nd Car won’t go into 4th properly, it over revs and then slams into 4th when it’s hot (but not all the time)

3rd Car begins to have difficulty managing the shift from 1st to 2nd

All the above happened over the space of a couple of days so I took it back to the transmission place and it was checked it. It gave out the fault code for a bad neutral safety switch, so he replaced that. He also replaced the S1 and S2 solenoids to make sure they weren’t part of the problem as well.

Driving it home from the workshop it ran in to a big problem, when approaching the lights and braking to stop the car it sat at 1500rpm then climbed to 3000rpm and would not go down. The car was shut off and restarted several times and it would not go down from 3000rpm. I checked the accelerator pedal and it was not stuck down. Called RACQ out and he could only get it to drop the revs by tapping the TPS. As its dual fuel and it was dark they had it towed to my mechanic to be sorted out.

The mechanic and workshop manager both looked all over for vacuum leaks, took the top off and cleaned the throttle body, tested everything, removed and replaced all vacuum lines etc and it would not stop over-revving. Turned it off and on a couple of times and then it stopped playing up and idled/accelerated/decelerated correctly. To be safe I had him replace the TPS and ISC even though they appeared to be functioning fine. I took it home and found the following:
1. Car doesn’t like shifting into 4th (again) it won’t shift to 4th until I hit 90kmh and about 2400rpm and then it tends to drop back into 3rd after a couple of min. It just doesn’t seem to want to engage 4th

2. When slowing down to stop it thumps back into 1st with a loud bang

3. If I take my foot off the accelerator the car maintains revs and speed almost as if it’s on cruise control, it will eventually decelerate, but very slowly and it takes a long distance. It feels as though it doesn’t want to change down through the gears

4. I also noticed that since the rebuild the speedo needle jerks round the gauge, it reads the right speed but it doesn’t smoothly move up and down anymore

To make sure the shifting problems aren’t related to the ECU I replaced that on the weekend. The transmission hasn’t changed the way it’s behaving.

Now at this point I am ready to tear my hair out. I’ve had a full rebuild on the auto, and within 4000k I’ve had a replacement S1 and S2 solenoid and a neutral safety switch. I am still having problems with the gear changes and I just want some advice as to whether it is an issue with the gearbox itself or something else before I go and argue it with the transmission centre.

Sounds more like external electrical.

I've seen all these faults (apart from the neutral switch) either caused by a dud/sticking TPS or bad speedo sensor signal.

The ECU requires very accurate information from these sensors to determine shift timing and pressure.

Maybe take the speedo sensor out, make sure the teeth on the cog aren't broken. I've had broken teeth once that caused bad shifting. I've seen a speedo sensor cause cruise control to play up because the sensor was a tad too far into the box. Maybe even try a difference sensor, they are a dime a dozen at wreckers.

Also check the TPS is returning to its base when you drop the throttle. Stick a multimetre in the plug and pump the throttle. Make sure it goes back under its .9v at closed throttle and doesnt stick on the way closing.

You said you have gas. Do you have a gas ECU that is taking readings from the TPS. This can cause problems with the TPS signal to the Ford ECU.

the intake manifolds not loose, where it bolts onto the head, is it?
also try another map sensor, that can also cause some of those symptoms you are seeing