severly lacking power

i have a 1993 gmc safari i have replaced all vacume lines that i could find to be bad i have 19Hg steady vacume at idle it seems to run good around town
but when i floor the gas pedel it has very slow pick up and engine winds
out on the highway when i floor it, it actually slows down when i slightly let off i can feel it increase power any help would greatly be appreciated oh yea the engin is 4.3 vortech engine code z
HAPPY HOLIDAYS

Welcome to AF. Lots of possibilities here, recent fuel filter? checked fuel pressure, possible cat going bad. Basic diagnostics.

i have a 1993 gmc safari i have replaced all vacume lines that i could find to be bad i have 19Hg steady vacume at idle it seems to run good around town
but when i floor the gas pedel it has very slow pick up and engine winds
out on the highway when i floor it, it actually slows down when i slightly let off i can feel it increase power any help would greatly be appreciated oh yea the engin is 4.3 vortech engine code z
HAPPY HOLIDAYSallrighty problem solved it was the fuel filter thanks
i am posting a new answer to a non start when cold problem i think every body will save a lot of money