'97 4.3L Running Rough, Tach Jumping

We have been having issues with my son's 97 Sierra running rough when it is cold/damp. It feels like the engine is missing.

Today, which is warm and dry, it started running really bad and it was all he could do to limp it home. It seemed like it wanted to idle fine but when he tried to rev it up the tach would start jumping and it seemed like it was missing.

Could this be a bad cap/rotor?

The engine has 200,000 miles and we've never changed the cap/rotor. I changed the plugs/wires probably 100,000 miles ago.

Any thoughts as to what I should be looking at would be greatly appreciated.

Hmm how about a complete tune up including fuel filter, with that mileage this is just maintenance, also check the fuel pressure, 60-65 psi.

Yeah, it's needing it! LOL

I limped it to Auto Zone today and had a code P0300, multiple random misfires.


I replaced the cap/rotor cuz it's never been replaced since I got the truck at 45,000 miles. I got it all put back together and it was running worse and the MIL was flashing! I thought great it's something major, but before I got too panicky I rechecked the cap............probably see it coming.........dumbass me crossed the 1 and 5 wires when I put the new cap on! DUH!! It runs a lot better now! LOL

I figure I'll do the plugs/wires next paycheck.