My lexus will hardly accelerate when it is still cold. After it warms up, it will start to shudder when I accelerate, usually around 45-50mph. I have had a bunch of work done of this car in the past 6 months, and my mechanic cannot figure out when is wrong.
Shudders when accelating on 1992 Lexus ES300
The on board diagnostics are not very advanced on that year of car (it only looked for shorts or opens in sensors at that point not performance of various sensors. Lack of acceleration from cold and shuttering on acceleration could be many things but I would start with ignition, your car has a conventional distributor, ignition coil distributor cap and rotor. I have seen the ignition coil fail under load (I use a coil tester to stress test the ignition coil to see if it breaks down under load. Remove the ignition cap and see if there is oil in the distributor (there shouldn't be) inspect the rotor and cap for cracks. Check the insulation of the spark plug wires. Check the air induction boot from the air filter housing to the intake manifold for cracks, then check that the fuel filter has been changed and verify fuel pressure and delivery. These are a pretty simple car. Would love to know what you find wrong!
I had this same problem with my 1994 es300, I got the motor mounts changed and the problem stopped.