1994 Lexus LS 400 codes 13,21,28

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It seems as though your vehicle engine may have jumped time. Check the timing by inspecting for loose and jumping teeth of the timing belt. Adjust valve timing or replace the timing belt as needed Let me know how this goes. .

It runs fine at a low speed when you give it gas it bogs down and takes a long time to catch up. It's getting too much gas for the mixture needed. I have replacd the cats, all o2 sensors, the TPS, the crank sensor. I don't know what else could affect the RPM signal. No codes come up for the cam sensors.

As stated before, incorrect timing will effect the RPM signal and is most likely the cause. This definitely needs inspected first.

Bob and Ken; It took me and a pretty good jack leg mechanic 3 days but we replaced the timing belt, it was 1 tooth off. The RPM signal code did go away but when I accelerate it bogs down and dosen't even try to catch up. Codes 21 and 28 come up. I just replaced both of these O2 sensors from O'Reily's. The plug ins were differant so I cut off the old ones and spliced them to the new ones. When I accelerate slowly it will attain hwy. speed but if I accelerate hard it goes to nothing. Any ideas?

Ecu I'm guessing did you ever figure it out

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Cheers, Ken