trying to solve an issue

have a volvo 740 with the Regina ignition

getting 3 codes at the moment
on the 6 pin 143....knock sensor had bad connector...fixed back again after 3 replacements has never shut off when cleared.
this never noticeably affected the running of the vehicle

on the 2 pin
121 code Map sensor few months back...code motor started running bad couldn't push down on accelerator without motor sputtering can get up to hwy speed but not with out sputtering till get there.

Replaced sensor from "u pull it" yard and replaced dry rotted vacuum elbow
car ran well and code cleared

car started acting up again code 121 same symptoms
replaced sensor from u pull it again...no change(ok maybe bad part)
again...no change...hmm
checked wiring and sensor
I have just over 5 volts on the positive
ground appears to be good less than 2 ohms (which I get the same reading touching my leads together directly)
and the sensor line is giving just under 5 volts when ignition on car not running( zero vacuum )

still have the code

now today on the 2 pin getting 122 code air temp...not done any diagnosis here

any thought?

it is behaving kind of like starving for fuel
I think there is a hint here I have a computer problem.
how would you trouble shoot it?

thoughts?

Thanks