I have an 88 GTA with a 305 TPI with what I think is an electrical/ignition system problem. At times while driving or sitting at idle in park the tachometer will spike or jump. I recently installed shorty headers so I put new shorty spark plugs in and replaced the plug wires since one was melted from rubbing up against the old exhaust manifold. The cap and rotor are over a year old I replaced them when I first got the car. I also think the car may have a small misfire that seems random. The car runs great at high RPMS but seems sluggish at lower RPMS sometimes. At first startup after sitting a while car starts fine then stumbles a bit then idles okay when tapping the gas pedal car is slow to respond. Any advice or help would be much appreciated hoping to have this figured out before I put the car in storage at the end of the month thanks.

 

Has a bad plug wire still

 

Last night went and started the car since its been sitting since Saturday, fired right up idled well then this random knocking started. Still has a misfire but this time it seems like a hard miss now. The knocking sound is random it doesn't have any consistency too it speed does not affect it. No SES lights. I'm going to put the old wires back on and see if that changes anything because the car seems to be running worse and the only thing changed was the wires.

 

Make sure you put the wires on snug since that was the only thing that's changed in between now and then.

 

Another vote on wires check them all again