1987 Blazer 2.8 "Shuttering" ...like a miss?

[69Firebird4-speed]

My 87 Blazer 4x4, 2.8, just started this...kind of a miss usually in overdrive. The check engine light has not come on. It started sounding rough at idle, so I thought it might be fuel filter or pump, so I changed the filter first. It did not fix it. It seems like it does it more when driving and the temp reaches about 200...I've been downshifting into drive and it doesn't do it as much. I thought maybe it was the trans, but it seems to drive better when it is cold...It sounds rough at first start-up, but then drives OK until temps reach 200, then starts the intermittent miss, thanks for any info or help. I'm going to check the codes this weekend, just figured I'd get a head start! Thanks Guys.

[blazes9395]

This sounds like either a weak ignition, or a weak combustion. When was the last time a tune-up was done, plugs, wires, cap/rotor? How is the EGR system working. Unplug the EGR valve and see if it changes anything. Of course this is assuming the engine is in mechanically good condition, with good compression and timing is set as needed, etc, etc.

[69Firebird4-speed]

B, It started to cut-out pretty bad on the way to work this morning...lucky I work at a wrecking yard! I "limped" in, sputtering and cutting out. I jumped on the "loader" and found another blazer...raised it up and got the pump...I stayed over, after work, in the shop and "cut" an access hole in the back and changed the pump. I wouldn't do that on a customer's ride, but no big deal on mine...easier than dropping the tank! It seemed fine on the way home, till temp hit 200 again and started the intermittent miss...I guess I'll go ahead and change out the plugs and wires...maybe the module...sure did seem like a fuel problem this morning. I get kinda spoiled on my "access" to parts at the yard. I'm going to actually have to spend some money now. Thanks for the reply.