Engine shakes when starting.

[95MustangV6]

Ok so ocassionally when i start my car as im cranking it my engine and entire car has started to shake.
Its kinda annoyying and i dont know exactly what it is.
I had a problem when i first got the car with the left motor mount. it was totally shot and i replaced it and was gonna replace the one on the right but it was gonna be hell and it didnt seem to be bad.
I have a feeling it might be the culprit for this problem.
Anyone else ever had this problem let me know what you think?

 

[bonestock3.8DTH]

Ive had this problem too. But I haven't a clue what does it cause after a few minute's it goes back to idleing right. It uselly happens to me when I haven't drove it in a while and it's been colder.

 

[7.5spool]

mine does it, i think its from improper balancing from the factory but i could be way off. my car idles at like 600 rpm and i rev it up to like 750 maybe it will shake. never bothers me really