Hello, 

I own a tacoma 1st generation 2003 double cab 

3.4L 6 CYL engine 

2 WD automatic transmission 

I am not original original so I can't tell 100% how it was serviced before me. 

I owned this car for nearly a decade , prior to me owing it had 2 other owners. 

Truck has 300,000k miles on it, when I bought it it had about 190,000.

In the time  that had it I haven't really had much issues with it other than changing a : gas cap, sensor.

My last major job was some issue where it was eating the thread on my wheels completely  and after some bearing and both control arms in the front were changed + alignment it seemed to solve the issue. 

The other things that I  replaced was normal things: brake pads, tires, headlights, engine oil/filter/ ac filter , and most recently too the door lock actuato( you know things that normally wear out after use and has to be changed)

I dont recall ever doing a transmission fluid change since I owned it, and really have no idea if previous people did. 

Recently A year ago it started leaking oil from what appears to be the transmission. Not a lot but I noticed it.Besides the leak the car drove and operated fine with no issues.  I don't service my car for these types of things As I don't know  the tools, space or knowledge even to do this so I took it to a mechanic.  so the leak lingered for about a year ( almost exactly a year) until it got ''fixed'' just recently.

Used a 3rd party mechanic and not dealer and called quite a few of them to get different perspectives. To say the least I picked the one that sounded the least sketchiest but even then you never really know what the heck these guys do.

Anyways they replaced a seal and the oil pan gasket and it seemed to stop the leak. Supposedly mechanic has done this service on older vehicles before.

Got the car back drove it for about 20 miles and seemed fine, no noise good handling nothing it worked the same as before just no leak anymore.

Well the next day I drove it a bit more ( about 45 miles)  and this is when I started noticing when I change a gear it wont detect it on the first try. 

The gears ( so far) dont slip while driving , there is no check engine light, and vibration or weird noise i can hear ( so far) , goes up hill fine  but when I park the park and then try to reverse or put it in drive it just wont move it stalls and doesn't move ( engine just revs ) . To fix this ( or how I have been able to get the truck going) is I just put it back in park and change the gear maybe twice or 3 times and then it registers it. Sometimes if I put it in reverse or drive after it was in park , I let it sit for a minute in that gear and then try and seems to work sometimes.

While I don't want to think negative , mechanic that did this service was going to ''take a look '' at it again. I use ''look'' because well we know how these things go sometimes with mechanics 

So I am here hopefully looking for some answers  or possible pointers of someone who has had a similar issue from a high mileage truck like this and managed to resolve it. Looking at videos online and such it seems some people have managed to resolve it by draining and refilling like 3 times  but not sure if that's advisable.