Timing checked? Be sure the vacuum/mechanical advance are working as well, can make for a flat/stumble. What year is the van?

 

1985, it has about 120,000 miles.

 

EGR still on the van?

 

All still original

 

Could certainly be a carb issue if its original or wasn't rebuilt correctly..

Timing, vacuum advance, EGR can cause a stumble, cough etc. All should be checked. Along with the accelerator pump as mentioned. Stable/smooth idle? No vacuum leaks, PCV or?

Timing spec?

Accelerator pump gives a good stream on a throttle snap?

Apply vacuum to the advance unit,, engine speed up at all? or does the timing advance when checked with a light?

If it still has EGR, try unplugging the small vacuum hose and plug the end, test drive, stumble still present?

 

Is the EGR necessary? We don't have smog testing for tags here. A new EGR is about $60. This is just an extra vehicle. Probably don't drive it more than 100 miles a year but need it to run good when I do drive it.

 

Idles smooth. Timing advance works.

 

how long has the van been sitting around without being started? it's starting to sound as if it might have some old gas in it that ain't quite up to standard

 

I drive it 3 or 4 times a month.

 

I think it's time for a kit to be put in the carb. that shouldn't be too trouble for you would it? what year of van is that thing any way?