1996 GMC jimmy surging

I have a 1996 GMC Jimmy that surges when driving. I have had the spider replaced about 1 year ago and the Jimmy has been running fine up until about 3 months ago. We have replaced the distributor, we have given it a tune up, all new wires, spark plugs, we have tested the fuel pump for pressue and that is fine.

While driving along it keeps surging most of the time driving, like every 3-5 minutes etc it will start acting up surging. I tried giving it more gas to see what happens, and it just kind of goes into more of a surging fit, cuts out like it is getting no gas but it never stalls, just surges. We tried not driving in overdrive, and that didn't change anything.

Anyone have any ideas, other then junking it.. It is in good shape, just wondering what else we could look at.:banghead:

I assume no cel's, so I would check the fuel pressure under these conditions( 60-65) then do a full scan, also was the dist gear worn when you had it out?