1993 Toyota Camry Won't Shift into 2nd.

In the original my reverse was slipping, After I got it back it stopped slipping, They've been looking at the car and they've checked and replaced and checked and replaced some more. It happens a lot less now, but It still happens once or twice a day. Is it possible a wire is grounding out somewhere? I mean it has to be electrical, that's the only way to explain the randomness of the occurences but I have no idea what it is. The ECM has been replaced and so has the ECT power switch, because it sometimes didn't work, it still does the off and on thing, but I have no idea why. A ground maybe? I checked some of them myself and they were ok, also the mechanics at this auto shop have regrounded it in different places to be sure.

I just don't understand why it would happen twice in a row with completely differen't tranny's. Especially if it's internal. I had 2 motor mounts replaced right before I lost second. And now it's just every now and again, reving the engine in neutral seems to get it to go through second, but My new question is, is there anything they could have switched over to this tranny from the old one? I mean you said the lines, well could they have used the same ones? Or are those literally inside the assembly? I'm just clueless with this car. Toyota's are supposed to be reliable. I got a real Lemon. Someone has rolled back the odometer. It says 138,000, but I know it's closer to 300,000. On the original engine, when it was replaced, it showed that the serpentine belt had been replaced at 178,000 and the date said '99. We've put so much money into this car, if we would've known we were going to spend this much either way I would have a baller car right now, instead of a '93 Toyota Camlemonry. I even thought of looking for a camry with a seized engine or shot tranny and having some place put in my car's engine and tranny. Weak huh.

Thanks for your help. I finally just got fed up with it, so me and my dad took it to Aamco. It's there now, They're running a diagnostic on it, and they're supposed to be the experts, so I hope they figure it out. And once they do, we're going to take what they say back to the shop we had it done at and show them. If they say it's the transmission, the warranty should still cover it. And I'll raise some hell if they try to tell me otherwise.