I was driving my wife's automatic '66 Dodge Dart 270 (slant-6) for about a mile when I heard a loud CRACK and the engine almost stalled, but then it immediately seemed fine. I looked in the rearview mirror to see if something had fallen off, but didn't see anything abnormal.
About another 4 miles later, I heard two more loud CRACKS in rapid succession, the car again seemed like it was going to stall, and this time I saw a puff of black smoke in the rearview mirror. Now I don't remember what exactly happened next, but I remember thinking it seemed like the powertrain suddenly didn't have as much power (I suppose maybe it downshifted and slowed down). After this, I parked it as soon as I could, which was about half a mile later. When I popped the hood, nothing seemed particularly out-of-the-ordinary except that one end of the bungee strap that was holding the battery was loose.
I'm hoping the CRACK sounds were just the bungee strap coming loose, but I don't know how it could have made the sound three times...I would have expected the strap could only come loose and whack around once, and I wouldn't have expected it to cause the engine to almost stall.
I'm hesitant to take it to the shop unless I can reliably reproduce the issue or something is obviously and visibly broken. I've also been trying to learn to fix my car myself. What are some things I should check?
More background (may or may not be relevant):
- The oil was last changed in the spring.
- I've been driving the car in-town 10 miles round-trip to and from work for about half of the summer, otherwise we were only driving it occasionally (maybe once a month on average).
- The car usually has trouble starting on the first try. It'll start and immediately stall. If it's warm out, I can pump the gas pedal once and it starts up fine. Otherwise, it might take a couple more tries and I have to let it warm up for 30 sec. to a minute before I can drive off (otherwise it stalls as soon as I put it in gear and push on the gas).
- The car was almost out of gas a couple days ago when I put in 6 gal, so it should have still had 4-5 gal. (though a few months ago I'm pretty sure someone tried siphoning gas from all our cars)
- I fill it with 87 octane (non-ethanol) gas because otherwise the engine stalls a lot.
- Sometimes when pulling away from a stop sign or light, the engine sputters and almost stalls, then suddenly goes back to running fine.
- The power brake booster has been removed, so it has "manual" brakes.
- I haven't used the parking brake recently