96 chev pu lacks power and surges

I have a 96 chev pu 2wd 4.3 v-6 5-speed.It starts and idles good.Sometimes runs good.Then you start driving it will surge and loose power and then it will start to run right and go on.I put on a new fuel filter didnt help.It probably needsa good tune-up but it seems to be starving for fuel when it runs bad.Could it be maf sensor or something like that? thanks phil

Yes, a MAF sensor is a possibility. At idle, tap the MAF with a screwdriver handle and if idle changes, the MAF is bad.

had a bad map sensor on a 99 5.7 that acted like that. It did not set a code, but my freind (GM Mechanic) noticed low values... (out of range).