HELP 98 GMC . Do i need a new motor?

What is your question?

1998 gmc 1500 I would like to keep my truck. it was my first truck, the love and nostalgia is there. Power issue, she spits and sputters, sometime stalls. Wasting gas having to accelerate faster to keep her going. Ive replaced the spider, made sure no exhaust leak, not a timing issue, manifold gaskets have been changed.... i dont know what to do. i was wondering what is compatible with this truck if i do need a new motor? i dont need it to fly down the road but to be able to cruise from time to time is nice. is a 350 long block too much? opinions please and thank you 4.6 V6 vortec 280,000+ miles

What makes this problem better or worse?

Raining days or foggy days it runs worse.

How long has your 1998 GMC C1500 had this problem?

MONTHS