ok so i have an 1992 sc400 with accelerations problems when running at speed of 35-45 mph. at those speed the the car stops accelerating like if i would of let the gas go and then it start to accelerate again and it keeps doing it repeatedly. i have to give more gas to make the issue stop. any suggestions of what could be causing the issue?

 

Do you have TRAC on yours? If you do, disconnect the trac plug on the throttle body and see if that helps to start.

 

Missfire?? Codes?

 

I say the same thing. Any codes? Thats the speed where it seems in my research that the MAF causes some problems.

Could be so many things that would cause this. IACV, 02 sensors, plugs, wires, caps, rotor button, MAF, and TPS.

 

i do not have TRAC on mine. i putted tps, iacv, efi relay, both coils, throttle body, spark plugs, spark plug wires, cam shaft sensor, o2 sensor one is new, main relay, MAF new, ecu and fuel pump and fuel filter. only thing left is rotors and caps. and about the codes i haven't checked if it throws anything im going to check that out tonight. i took it to some shop and they told me it does has a misfire but they don't know what it is for sure. i changed the ecu because the car had an rpm surge which it was a pain to solve... lol i have a new fuel pump ecu that im planing to put as well. also when i put the car into drive it jolts significantly. when i'm on the grass or lose ground it spins the tires just when it jolts and on hard ground it doesn't .

 

On the jolting in gear, I say the RPM is set too high, causing this. With all the other things you have replaced, how are the cats itself? I would also look into the caps and rotor button. Could have some rust/corrosion build up on the tip.

 

Another issue on the jolting is the tranny and engine mount are both bad. Check them while you are under the car.

 

rpm set to 600 when warm when its cold its 800 im thinking maybe a transmission solenoid? the transmission mounts i replaced them already the engine ones are good sometimes it doesn't jolt but most of the time it does.
about the cats i replaced one its new the left side and the right side seems good doesn't have any pressure building up. and the rotors and caps buttons i checked one on the driver side its clean the other one haven't checked it out yet will that tomorrow. thanks for the great support