Ls400 Poor Performance

[dadsls400]

Hey all, i just replaced my engine comp(after waiting nearly a year before i could find a used one for a 94 at my local salvage yard.) brought it home,installed it, started car up& it ran perfect, no cel,no trac light.I was stoked,took it for a 20 mile drive no problems at all, i thought it was all good,so i went and fueled it up,(premium) leaving the station i accelerated & it stumbled like it did before the computer issue,but no cel, no trac light just stumbled let off the pedal slightly it runs perfect. I drove it some more then noticed it is very intermittent sometimes it does it sometimes it does not. I think some of the problem i had before is resolved with the new computer(before the cel and trac lights would come on with any acceleration & car would buck)Now it is once again drivable,but not smooth like it should be,or like it was when i first replaced computer..Anyone have any solution to where to look? Again, no cel,no lights at all& car idles perfect. Also, to the floor it accelerates just fine,it seems to be just one place during acceleration it has the "stumble" problem

Thanks in advance, Skip

BTW both tps sensors And mass air meter are new,thanks to my other comp giving codes saying they were the problem @ $800

[etex]

This may or may not help, but I would remove the negative battery cable for a few minutes and then reconnect. Just my $.02.

[billydpowell]

good idea, it works sometimes.....

[dadsls400]

I tried that to no result, thanks for the suggestion guys. Let me define "stumble" its just like a cylinder comes and goes, i doesn't miss, its just like it struggles then cleans up, then struggles again

[curiousB]

Had car been sitting unused for 1 year? If so maybe fuel is stale, try adding some fresh plus maybe an additive like Heet to displace any water in the tank.

Sure sounds like ignition related though. Maybe an intermittent coil causing a bank of cylinders to drop in and out. I assume you checked the obvious like moisture inside distributor cap. Sometimes the wires can arc against the chassis and cause missed spark at plug. Look under hood in darkness. If there is arcing you'll see it. Also might want to check crank position sensor. Often cited as a problem.

Good luck, there should be a way out of this without too much trouble.

[dadsls400]

Had car been sitting unused for 1 year? If so maybe fuel is stale, try adding some fresh plus maybe an additive like Heet to displace any water in the tank.

Sure sounds like ignition related though. Maybe an intermittent coil causing a bank of cylinders to drop in and out. I assume you checked the obvious like moisture inside distributor cap. Sometimes the wires can arc against the chassis and cause missed spark at plug. Look under hood in darkness. If there is arcing you'll see it. Also might want to check crank position sensor. Often cited as a problem.

Good luck, there should be a way out of this without too much trouble.

wouldnt the cps ignight the check engine light?

Thanks for your input..