Hey guys, 1990 LS400 is giving me trouble again. I was driving to work and I felt it miss once lightly then quit, through the 20 minute drive it progressively got slowly worse. Very hard car shaking miss when it was under load like going up slight hills.
After work it idled just fine but went back to missing on the drive. My first thought was something ignition wise as I had recently replaced both distributor rotors, plugs and wires. I checked all my work and found it satisfactory but after waiting to see how long it would idle before missing it started hard missing sitting in park. I let it sit for a week or so to deal with finding a temporary vehicle and upon starting it again it was missing all over the place, having owned one before I thought I was lucky and the ECU went out.
So I ordered one, slapped it in, and though it improved it is back to that intermittent miss it had before the ECU went out.

These are just me airing my thoughts here:
Though the radiator has a leak i kept the coolant at an acceptable level and trusted my gauge as it never raised in temp. (I have trust issues with head gaskets due to ford) so when i pulled the plugs I checked the cylinders which weren't clean but they were dry.
I'm considering a fuel injector issue but that does not sound right to me due to the miss being so intermittent and across cylinders.
Maybe the fuel system in general? I haven't had the time to put it on a lift to work from the tank up
Maybe a fuse/relay related to ignition I need to look into?

If anyone has any advice it would be greatly appreciated, or if you think these ideas are not worth pursuing please let me know.

 

Do you know if all cylinders are getting fuel and spark?

One thing you didn't mention checking are the ignition coils. There is a test procedure for that which I've posted in the past and you can find via the forum search. Look into that

The igniters also should be checked. Follow this video: