Ok my 94 ls had been giving me problems with idling after long highway drives, I was aware that this was a common issue. Eventually it got so bad that when I would start the car it would not idle unless I kept it revved. After searching the forums I concluded it was most likely the IACV. I ordered a replacement part off ebay, new one cost 5 to 6 hundred bucks ouch! I also cleaned the throttle body which really didn't seem to dirty. After installing the new to me IACV, I started the car and it fired up but now the rpms are repeatedly bouncing between 1500-1900 with my foot off the pedal. Also with the engine running in this state there is a gasoline smell coming from the car. I checked all the hoses I removed during the cleaning and part replacement and they seem tight. Before I replaced the iacv the engine would not even start but now it will start every time it just has this problem. This car has close to 185k and has had the timing belt, water pump, plugs and one of the coils replaced in the last 1.5 years. After searching the forums I am thinking it could be a fuel pump, fuel filter, fuel pump ecu, and possibly TPS sensor. I tried checking for codes but since i had the battery unhooked there were none stored. This car is a non TRAC model. Could this be a vacuum line leak somewhere? I have basic tools but no multimeter for testing, and the nearest lexus dealer is 300 miles away. I do not know any mechanics in the area and I don't wont to sell an appendage to take it to the toyota dealership. I am starting to think it may be fuel related but I am not a mechanic. This is one of the few times I have not been able to fix this car by searching the forums, and before I buy anymore parts I would like your opinions on this, thanks in advance for your time and help!

 

1 thing you should do is buy a multimeter, you can get a cheap one for around $10. That can help you test any of the sensors on the car. If you had one before you probably wouldn't have had to buy the IACV, it might have just needed to be cleaned. (But that's in the past) You can check the AFM and TPS, this has helped alot of people; https://www.clublexus.com/forums/sc-...on-issues.html
Something I would change without even checking it is the ECT, it helps in many ways and it's cheap enough. ($25 at Autozone)

 

What does ECT stand for? I'm thinking of the little switch on the center console?

 

Engine Coolant Temperature sensor. This is for a 95 but it's the same exact thing as your 94; https://www.clublexus.com/forums/ls4...ange-pics.html After reading again, it does sound like it's vacuum related so ya might want to check all the vacuum hoses and everything, especially around the area you were just working in. Maybe there's a cracked hose, they do get pretty hot and over the years they get hard and brittle.