ok have a nice 1999 rx300 200k a few months ago code showed coil misfire so replaced coils. few months later check engine light and running rough and almost felt like it went into limp mode would not shift to higher gear so took I took to mechanic and it was an oil pressure sensor that he replaced and also MAF sensor. picked it up ran good till I got a few miles on interstate and check engine light came on again. what I did notice is that it didn't seem to shift into overdrive. it went through the 4 gears fine but I was running aroun 70mph at 2800rpm which is high. took it back andnoticed the oil sensor or whatever he replaced needed fixed. so took it home and ran fine for a few days then the exact same thing. this time showed o2 sensor, VTS, (oil sensor) and lean. he replaced the same sensor with a new one. all lights off then drove it 40 miles on backroads to and from work with no problems. but when I picked it up and got on interstate to high speeds (still seems like OD not kicking in) the light came on again and running rough. now he's stumped..........anyway, I don't wanna drop a BUNCH of money in it but it drives great besides this recent issue. I wanna sell it to get a little civic to commute. any suggestions on a fix?

 

Same thing after engine was warm it would not go in OD, on my 2002 it turned out to be the 2 knock sensors in motor after I replaced both sensors transmission shifts fine. Cost about 500 for repairs and 250 for sensors.