91 Ls400 165k Stalled Going 65mph On Freeway,yikes

[91LS400150K]

My engine has stalled 3 times on my 91 LS400 with 165K during the past 3 months, each about a month apart. First 2 times I was stopped at a light and the engine stalled. The first time started it right up and moved on. Second time, started right up but sputtered along for 200 yards while I was constantly pumping the accellerator to the floor trying to get a response. During those 200 yards, I'd get about a <5% power with the accelator to the floor TWICE. The other 25 or so pumps gave me nothing. So after 200 yards, it stalled, I restarted, problem disappeared. Then 2 days ago, the engine died while I was going 65mph for about 40 minutes. Moved over 3 lanes asap to the shoulder while furiously punching the accelerator with little to no response. During the next 5 minutes, I tried about 10 times to start the car and floor it into traffic but was getting 1% response from my accelerator, inching along at 2-3mph. About half those times, the engine stalled while idling. The other half of the time, the engine will start revving at about 450, then drop to 250 causing the engine to knock and the car to shudder, then either blast off to 1250-1500rpm and then repeat and then maybe repeat again and then die. About the 11th try, I got out of there, floored it to 70, exit was half a mile away, coasted to the light and the car promptly stalled. On the second try, got the car to move 40ft at 2mph furiously slamming the accelerator to the floor, then stall. Dealer was 5 miles away, car stalled maybe 5 times on the way, 3 times at a stoplight (I always stopped off to the side at the light like I was parked in case...) and twice while moving at less than 30mph. Arrived at the dealer, told them they needed to look at it ASAP, they looked at it 2-3 hours later, say it's tip top. Btw, I only use 91 octane. Reading old threads, it appears it could be one of many items at fault. New spark plugs and wires, throttle body needs cleaining, new fuel injectors, new PCV valve (mine does need replacing, over 30K on it I think), and water in the gas tank. Maybe my old gas cap doesn't properly vent and I need a new one. All my stalling incidents occur with 3/8ths or less of gas left in tank. Also, 95LS400Bob has posted "On many vehicles I have worked on that have stalled or quit, that never show a trouble code or a check engine light, that the dealers were always unable to find the problem has always been a crankshaft or camshaft (most engines use one or the other) position sensor." This could be it if it also applies to the 91 LS400 since the dealer can't figure it out. Does anyone know how much an independent Lexus shop should charge for a new camshaft position sensor? Also, what's a fair price for a PCV valve replacement? Thank you all in advance for your insights and I'll definitely keep you posted on my progress.

[flanker271]

My engine had similiar irragular behaviour 2 monthes ago. While driving on the freeway using cruise control, the car suddenly slowed down for no apparent reason and would not speed up even if I floor the pedel. After about 3 trys the car would suddenly down shift and speed up.

Similarily, at stop and go traffic the engine would rev up by it self for 1-2 seconds, then going back down to 300-400 rpm, then surge again, and then back to normal. During all this time I had to firmly apply my brake so I won't rear end other vehicles.

Had my problem checked at Precision Toyota of Tucson (they are very professional nice people), the problem turned out to be the left crank shaft positioning sensor. During my last timing belt change (not at Precison Toyota), the mechanic did not properly seat the sensor wire into it's groove, causing the wire to rub against the timing belt and caused a huge cavity, totally destroying the sensor. Precison Toyota replaced the sensor for $375, parts and labour, and the problem went away. After some arguing, I got a full reimbursement from the timing belt shop afterwards.

This is just my case and might be different from yours. I thought I'd like to share it with you so you can be prepared when dealing witht the Lexus dealer.