Error code 144 1991 240. Stumped..

[Taylorlharris90]

1991 Volvo 240 auto.
I’m having an intermittent CEL, 144 ( load Signal missing from ECU to EZK ) code with the symptoms continuing whether the light is on or off. When I start the car the idle well shoot up to around 1500 and drop down to nearly stalling out before it settles around 800. Once it’s warmed up it idles pretty high around, 1300-1400 in park and 1100 in drive. I have replaced both computers, fuel pump relay, and cleaned and checked all fuse connections. I’ve also been through all of the vac lines. Starting to think the worst that there’s a wiring issue between the computer and the EZK. Any help on how to test this? I’m decent with a multi meter just not sure the procedures for diagnosing this issue.

Thanks in advance.