Lexus Sounds Like A Freight Train

[1999LexusGS400]

Ok so here's the deal, i need help please... I have a 99 Lexus GS400 with 173,000 miles. I have had trouble over the last couple years with the tranny. Check engine light came on, car started shifting rough into 3rd gear. Mechanic told me it was shift sylonoid C, so i replaced it. Same trouble came back. I gave up on that problem and kept driving it. When it came to 173,000 miles i decided tio replace the timing belt and water pump, so i ordered the complete kit with seals and pulleys. Took it to a mom and pops shop trying to save a buck. 2 days later, water pump starts leaking. It was a slow leek so just kept an eye on it. 3 weeks later, sitting at a light and idle becomes rough, give it gas and sounds like a train and doesn't want to barely move. Took it to the mechanic and he scanned the codes, laughed and said cylindar 2,4,6,8 are dead or misfiring. He then laughed and said i need a new engine. Engine has never burned a drop of oil, so cars been sitting for 2 months, charged the battery and started it today, 2 front door locks won't lock with remote. So im wondering, one side of engine dead, tranny not shifting properly, door locks... Electrical problem?

Any ideas or help would be greatly appreciated

[intakerGS]

Is this 'laughing mechanic' the same one that replaced your timing belt and waterpump? Did he wear a clownsnose and big shoes?

Anyway, there might be a (camshaft?) (sensor) timing problem, which can explain the misfiring of multiple cylinders. Perhaps there's some electrical problem (coilpack/plugwiring?).

At this point, it could be a lot of things, perhaps a single problem causing multiple incidents. It wouldn't hurt to specify some ECU faultcode readings, which can lead to a more specific advice.

My best advice would be to evade the mom and pops shop and get some serious advice and/or inspection from a proven, trusted and lexus experienced shop or dealer.

[SKperformance]

if one side is dead the timing belt skipped a few teeth on that side cam.

Get a proper technician to look at it .