Help! Auto transmission gets stuck in 1st gear and recovers after restarting!

[jackchoo]

anyone there who can help?? This is a S13 Auto transmission by the way...

update : I notice that it happens quite predictably :-

- from a cold start (after 2-3 minutes warm up)- after 6-7 minutes of driving- at that point I'm normally in heavy traffic so coasting real slow towards the freeway entrance- enter freeway, accelerate- and it cannot get out of first gear!!!- stop the car dangerously by the side- and its all ok for the rest of the journey! till the next cold start go back to the top.

It pulls out a code 43 when this happens (TPS) for the TCM and ECM. But I've already swapped with a good tps and have even checked it on a scope first.

One question though : is the TPS harness 0V reference supposed to be directly grounded to the battery. My multimeter seems to show a direct short to body/battery ground.