Hi
I have a 1994 +4 which I bought from a reputable Morgan dealer some 4 years or so ago.
The car was fully serviced and had new king pins fitted - it also had new front shock absorbers.
On a concrete dual carriageway, on my way home from Curborough,, I found that the ride was horrendous, with the front of the car bouncing so much that it felt as if the front tyres were leaving the road. Keeping it in a straight line was tricky too.
I eventually found that the problem was a very loose front suspension near-side cross frame stay (or crosshead) tie rod.
I adjusted this correctly and have since travelled may thousands of happy bounce free miles in it. Check out GoMog's crossframe stay adjustment.
I hope this may help you.
Good luck.
Geoff