So Ive had this odd popping sound coming from around my intake for a while, but nothing has been really going wrong with anything before now. After a day of driving across state for about 3 hours, and then just around town, I went to go home the next day and I started getting terrible engine shudder once the car warmed up. Its almost like a cylinder is intermittently dropping out, and then coming back in? But once I got on the highway everything was fine and ran like a champ. I replaced the spark plugs once I made it home and I found some oil in #3's spark plug tube, didnt seem like a lot, or enough to cause this bad of a problem, but maybe? Any ways, heres a short little video of it shuddering at idle (its been warmed up) and you can hear the popping sound as the rpm's drop down to a slow idle.

Things that have been fixed in atleast the last two years:
-distributor
-wires
-spark plus
-cleaned egr ports

 

Sounds like you need a valve lash adjustment something fierce. Pray it's not a valve or valve guide. While those are fixable they're a lot more money.

 

Yeah, that was supposed to be the job this weekend, but here we are. After doing some more research, it seems that it could be the vacuum solenoid on the rear motor mount. I honestly had never heard of them having a self-adjusting system, but I guess you learn something new everyday.

 

I had a brain fart and came back in here to tell you it could be a mount. lol. Totally do-able but, a pain to change.

What year and model?

 

Its a '90 DX with an auto tranny. When the sound first came about I automatically thought it was the mount, but I wasnt getting any movement out of the actual rubber within it so I just kinda wrote it off.

 

Engine mount may a count for the excessive engine movement. However, the rough running/engine miss would more than likely be something with the timing or valves. If it has been a while since your last timing belt hang I would look at doing that. The valve adjustment is pat of that service.