LS400 has been randomly stalling after 10-15 minutes of driving for about 4 months. Sometimes, It would start up and run again after sitting for 5-30 minutes. Often, it would turn over and immediately stall.

Yesterday, it drove for about 6 miles then started it acting up. After sitting for about 30 minutes, It started up again and drove a short distance stalled a few more times (sometimes in the left turn lane - yikes) and then drove another 16 miles before starting to act up again, finally dying on the side of the road. While it was driving, it was idling very low, around 400rpm. Then the battery went dead trying to crank it after it stalled again, and had to tow it the remaining mile to my place. I took the battery out to charge it, and today, it wouldn't start at all. Now it's my problem.

Previous mechanics were stumped, variously blaming the MAF, fuel pump and crankshaft position sensor. I believe all 3 of those things were replaced, but haven't verified that myself. At first, there was a check engine light and a code for the MAF, but this time, there's no light. I'm not sure if there are any codes, but I doubt it, considering I took the battery out. I wasn't expecting it to quit running altogether, and anticipated being able to check out the codes after a stall.

It seems the previous mechanics never did a very good job diagnosing the issue. My guesses are a bad camshaft position sensor, fuel pressure sensor, crankshaft position sensor still bad, or something similar. My next step is to back probe the sensors and see if I find anything fishy. Any ideas?