Bad ECM?

[86k5silverado]

Alright so here's the quick rundown. I've got an 86 k5 blazer with an E4ME quadrajet on a 305. The truck will have it's good days and its bad days. It appears as though when the truck is subjected to any type of load, the motor will bog down. I know this isn't a fuel system issue because I've already troubleshooted that entire thing. My next assumption would be ignition timing. The truck will drive, but you can feel all the power is there. I've rebuilt the factory distributor with all brand new components including a coil pickup. after replacing that, the truck ran like new for about a week but then began to act up again. My question is whether or not the ECM can be held responsible for all this. It definitely seems like a possibility to me but I'd like some other opinions as well.
Thank You,
CJ