[MichaelN]

'81 SC, 188K miles, no mods. Last Saturday took an extensive drive from Northern Calif. to Southern Calif on mostly back roads and returned Sunday via freeway (I-5). 800 miles total. On the drive down car was faultless with good power at all engine speeds and no problems. However on the drive back, shortly after getting on the freeway leaving L.A., the motor suddenly went completely dead for about 2-3 seconds and then back on again. Just like throwing a switch. No sputter, no gradually loosing power, just off...and then back on.

I continued on and it did the same thing about 10 minutes later. And then 30 min. after that, and about 45 min. after that, and so on through the afternoon and into the night all the way home. Sometimes it would go off for up to 5 seconds or so and I would start to move to the shoulder as the speed slowed, but it would always fire up again (I never took it out of gear when this would happen). Dash lights and gauges remained on and normal when this happened.

Everything looked normal on the engine when I stopped for lunch late in the afternoon, and the only thing I was able to do was make sure the leads on the coil and distributor were secure (did a complete tuneup around 5K miles ago) and swap in a spare fuel pump relay that I had in the glove compartment.

This morning I drove it a bit and everything was normal save for one peculiar symptom. The idle was, slow, rough, and irregular; barely above stall. But when I glanced at the tach it was showing 1,500 to 1,800 rpm. That was weird. Above idle the tach and engine return to normal.

I had previously gone through the receipts from the P.O. and found nothing that indicated that the fuel pump had ever replaced, so I bought a new pump and filter a couple weeks ago intending to change them last week. I got the filter in, but ran out of time to do the pump. So I'm going to start by putting in the new pump, but this idle/tach thing has me doubting that this will take care of it.

Any other ideas about what's going on here? I'm no CSI expert and I'm not that good with electrical troubleshooting either, so it's likely headed for the shop if the new pump doesn't do the trick, but I'm interested in any opinions.