what cause my vehicle not to pick up on high speed .works fine on local roads. on 1993 Nissan Quest

while driving on the express way ,i felt my vehicle is losing power,and i dnt know wat to do.yesterday ,itook my vehicle to the muffler shop and get the muffler change.please help me thank u.

Asked by for the 1993 Nissan Quest
Sometime a weak fuel pump can cause a loss of power. You need to ckeck the pressure and volume