I just bought my second sc300.Its a 95 with about 186,xxx miles.The car has some type of idle/driving problem.The guy i bought it from told me the maf was bad.And the maf on my other sc300 was bad so i thought.So before I left to go pick the car up i grabbed the maf off of my 87 supra turbo.So when i get there he starts the car it doesn't want to stay idling or drive.so to keep it running while driving it you have to keep your foot on the brake and gas at the same time to make sure the car doesn't stall.But if you have it in park and hold the gas steady so it doesn't stall the rpms will drop to what ever than they pic right back up but it keeps doing over and over like the tps sensor was bad.but when you had the key turned all the way forward (engine not running)you would hear a clicking noise.it sounded like a relay.but when it was clicking the check engine light would come on.but when the clicking stopped the check engine light would go out.So i swapped the maf out and the car idles but it still does the same thing when you hold the gas steady.So I go check all the clips in the engine bay that i can get to.to make sure they're plugged in.so they're was a clip that was under neath the intake manifold that when i pushed on it to make sure it was plugged in all the way you felt the lightest snap. so i thought might have been the problem.so he starts the car back up and it runs perfect.no problems what so ever.so i head home and about 45min later the while driving 65-70 mph the rpms drop about 400 rpms like the car was going to shut off then it goes right back to normal. so about 5min later it did it again and it didn't do it for about 10mins.so by this time im back in town and it starts doing it like when i was at his house before i messed with the clip under the intake.so i make it home and i pull in the yard put the car in park and it shuts off.so i start it back up to see whats going to happen and it starts doing the same thing it was doing when i was at his house.so i decided to go inside and mess with it tomorrow cause it was about 1:00 am.so when i get home from school i start the car and it runs perfect.so i swapped the maf out with the original maf and the car doesn't want to start.so i get it started and it runs just like it did at his house.so i put the supra maf back in and it runs good for about 15min.then it starts doing the same thing over not wanting to idle so i take the maf out of my other sc300 and it runs perfect for about 5min then it starts doing the same thing.so i switch back to the supra maf and it runs good for about 30min.then it starts doing the same thing.so i checked every clip that i could reach in the engine bay.and it still does the same thing.oh and when the car was driving and the rpms would drop the check engine light would come on until the rpms went back to normal.so i turn the key all the way forward and heard the clicking noise witch was not a consistent clicking.it would come off and on like there was a short some where.so i chased down the clicking nose and there is two noise one is coming from the senor that sits on top of the fuel rail.its right next to the fuel pressure regulator.it has two small vacuum hoses attached to it.and the other one was coming from under neath the car.so i jacked up the car and you cant really tell where its coming from.so i started feeling around for something clicking cause you can feel the sensor on top of the fuel rail clicking.and i couldn't find out where it was coming from but i felt the strong clicking feeling from the transmission pan.so not sure what the hell it could be.here's a video of the car in park and me holding the gas in the same spot.but you can see it really doesn't want to let the car stay at one rpm range.oh and watch the check engine light.sorry for all my misspelled words and messed up sentences.
http://www.youtube.com/watch?v=YLXgvs8QcLU

 

Nobody knows?? i need help.

 

check the vacuum hoses for cracks or just not making proper seals.

 

sounds like you have a fuel delivery problem. do a search for fuel ecu bypass, if the car runs with this done, then you need to replace your fuel ecu.

 

When i got the car the guy had already bypassed the fuel pump ecu.And i check the vacuum hoses i don't see any cracks or possible leaks.

 

Here's a picture of the thing that's clicking on top of the fuel rail.

 

I went and started it up and it runs fine for about 15min then it messes up.

 

i believe that clicking thing is a vsv switch. thats all i know about it.

 

thanks for the name cause i had no clue what it was.so i searched vsv on alldate and it has something to do with the egr and vacuum.but still not sure about the clicking.