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.