4" of vacuum from oil fill/vent tube, popping hesitation intermittent rough idle?

Ishman 306

Founding Member
May 18, 2001
67
0
6
St Petersburg, FL
I've been experiencing a popping hesitation from idle to about 3000k rpm. Idle is fine and then randomly feels like its going to die drops 300rpm, then cleans back up. Its most noticeable when cruising on the interstate...you will be cruising and it feels normal, yet all the sudden for a couple of seconds the car feels like it gains power and cleans up real smooth, then all the sudden back how it was driving. I've been trying to hunt down this problem for over a year now, replaced all sensors cleaned 10 pin connector, new distributor, then today I was looking at the vacuum at idle. I noticed when its idling real rough the vacuum drops from 16 inches to 11 inches. I connected the vacuum gauge to the oil fill tube and read 4 inches of vacuum!!!! I was thought that you were supposed to have positive pressure in the valve cover area?

Any help appreciated!
 
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