Truck was a 87 with a 700r4 and 305. Someone had done a hack swap with a 89 blazer 350 kept the trans.
I got the truck a few months back and got it running fine so just kept going with little problems.

Currently missing the o2 upstream and downstream sensors. Has headers.

Smog pump deleted.

diagnostic plug does not work.

Here’s the new issue I have. Start the truck and drive normal for a good 10-15 minutes then at cruising speed 45mph 1500rpm I feel the power bog down. I can give it tons of throttle and the engine gives me no power it feels like the timing is back crazy. Once I get enough Trans pressure to downshift it pulls hard then I let the throttle back to cruise and it does it again. I’ve tried staying in 3rd but it still happens while I’m at light throttle. I also get a jumpy acceleration. Like from a stop either it’s flat on its face or it jumps around until I’m past 2k rpm.

 

Fuel issue? Consider fuel filter change and check fuel pressure while symptoms are occurring

 

Fuel pressure was good.
spray pattern optimal.
all headers same temp.

tried some power braking while symptoms present and feels like a miss on all cylinders.

going to try a new ignition module. The one in there was new with the distributor but cheap and may have burnt up. Didn’t see any moisture.