Nissan Repair: 1992 Nissan Maxima SE 3.0 DOHC - Engines Runs Rough, nissan maxima se, compression gauge

Question
This problem just started today.  I started the car, runs perfect.  I drove it for about 5 mins, and came to a stop sign and once the car came to a complete stop the Rpm just drop immediately to 500 Rpm, I actually thought it was going to stall.  The engine just runs rough, the whole car just vibrates in sync with the engine.  So when I started to accelerate and the engine just started vibrating even faster with the Rpm climbing higher, and once I got to a higher Rpm it seemed to go away.  But it does this every time I drive it, and before it purred like a kitten so its a big difference in performance overnight.  I read other questions on this website with similar problems and same year and model; they said something about doing a compression check?  No idea what that is, I fix planes not cars; but I would like to learn.  But anything would be great, just give me every thing you think that would cause this problem.  I'm just trying to avoid going to the dealership again and getting my money robbed from my pocket.

Thanks,

Answer
Mark,

I would perform a compression check to see if the engine has jumped timing.  You could have jumped timing and this would cause the rough idle.  Also, while you are doing a compression check replace the spark plugs as they could be a cause if they are old.  Get a compression gauge with a flexible hose and remove all of your sparkplugs.  Screw the gauge hose into one spark plug hole at a time and, be sure the coil is disconnected, now spin the engine over a couple of revolutions, have someone do this while you watch the gauge.  Mark down the hole and reading.  Do this to all six and record the numbers.  If any are ten percent lower than the rest you have ring or valve problems.  If all are low you probably jumped timing.  A note of caution is to make sure you blow out where the spark plugs go with compressed air before you remove the plugs.  Sand and dirt like to cake up the access and if you just remove the spark plugs you will get dirt and debris in the cylinder.  Also, after you do blow off the spark plug hole spray a little lubricant down around the plug to aid in its removal.  It will also help trap any dirt that is in the threads.  Get NGK or Nippondenso spark plugs since they work well with Nissan cars.  Do not use Bosch.  I have had way too many problems with them on Nissans.  They seem to work great with other cars like BMW.