My 88 Dakota 3.9 quit yesterday, and I had to drag it home. It had begun running rough and would only go if I kept the throttle mostly open, then it quit. Based on what I saw when I was troubleshooting, I've begun to wonder if it could have skipped a tooth on the timing chain. The motor has 140K on it, but hasn't been a problem up to now...
I checked the cap and rotor, and there was a fair amount of wear on the contacts, so I replaced them. I checked for spark and have that. It smells gassy when I crank it, and it cranked faster than normal. Knowing that it had spark, and apparently gas, I shot it with some ether while cranking and it didn't catch at all. I know that the distributor is turning because it had changed position when I popped the cap off. To top it all off, the starter wasn't engaging reliably. Are there any timing marks that are external to the engine? Are there any other common problems that can cause this sort of thing?