Low MPG 1988 GM with 302 EFI

[Tanner02480]

With the belt on it only give the code 44 but I noted that only one of the two catalytics is plugged to the smog pump

[Tiggie]

Might want to check EGR function. Good post here: https://www.stangnet.com/mustang-for.../#post-8656265

Do the two cars run about the same? I noticed a difference from my 88 and 90 in terms of power and MPG; I suspect 88 has some weak compression issue.