So I'm driving my 94 Ram Van 318 engine/automatic yesterday and she started to cough and miss while on the freeway and then while at lower speed too. It ran perfect earlier in the day, lots of power, no misses. I suspect possibly bad gas cause I don't drive it a lot but not sure how to diagnose it. It does have fuel injection and about 150k miles. I replaced the timing chain, plugs, cap & rotor about 2 years ago too.

 

Try plugging in a code reader to see if there are any pending codes that might give you a clue as to what caused it.

 

I do have a code reader which I'll try this weekend. There's no check engine light on however.

 

Not all codes turn on the CEL, including pending codes.

 

Update - I replaced the coil on the chance that it may be intermittent then ran the Van down the highway about 20 miles without even a hiccup. I still suspect there may have been crap in the gas but I may never know. In any case, it smogged just fine which is why I ran it to begin with. I had put just 4k miles on it since the last smog check 2 years ago. I never did put the code checker on it, perhaps I will this weekend.