1988 Chevy Cheyenne engine running lean

i have a 88 chevy 3500 with a 5.7 tbi motor the truck when cold runs like it is not getting enough fuel or sputters but after about 25 min of drivin it runs fine but i get a check engine light but the truck has no sputtering or nothing no running hot truck runs fine but i have the c.e.l on i got a diagnostic test and it is reading a code 44 what are some causes