Error Code 43 on 88 1-ton dually

I have lost engine power on my 88 1-ton dually about 4 weeks ago. It would not run or start. I replaced the cap, rotor, plug wires, plugs, fuel filter and ecm. My prior ecm will not show any codes. The new ecm shows error code 43. This code shows an issue with the knock sensor or ecs. I can find neither on my vehicle. Any thoughts or suggestions are appreciated.

ok i'll see if i can help, i just went through a bunch of stuff on my 88 with a 350 in it.

what engine is in yours? any description i can give relate to the 350 motor.

1. do you have a manual, if not, get one.

2. knock sensor is located on the drivers side engine block just above the oil pan. kidna towardes the front. you have to get at it from under the truck. it goes into a water jacket so have a bucket handy.

esc is to the right of the tbi, a flat square thing, search autozone's website for a pic of it.

also check the groung wires by the top radiator hose inlet on the block. if they are loose or dirty that can cause problems with the esc.

also check the engine ground strap. i had a issue with mine where it was still connected but not working too well. i tested that with a extra battery cable i had around by clamping it to the engine and frame.

It is a 7.4 TBI. It is a somewhat unique truck as it is an 88 yet has the body style of the 87. I have searched the motor over and can find no knock sensor or ESC module. I have tried two new computers and get the error on each. When I move the PROMs from the old computer to one of the new computers, the error is not there. It seems that the old PROMs may be programmed to not have these two items.

The truck now runs, but suffers from lack of power.

I thought that the fuel pump might be an issue, but I have two saddle tanks and I believe there is a fuel pump in each tank and I doubt that both pumps would go out at the same time.