87 shelby lancer bucks surges under boost

[moparman7]

My 87 shelby lancer 5 speed has 93000 on the clock and started surging and bucking once it goes to boost over 6psi , I replaced plug wires pick up plate in distributor
Didn't help , it runs really good if u drive it normal , only does it when you put your foot in it...

[NAJ]

You have to determine if this is a mechanical, ignition or fuel issue.
1)Are any fault codes set?
2)What is actual pressure (boost) reading at the manifold, verify you are not actually hitting overboost shutdown.
3)Connect a fuel pressure gauge and vacuum/pressure gauge and go for a ride, is fuel pressure in specs for boost?
4)What is Map output voltage reading under the problem condition?
5)Verify cam timing and ignition timing are correct.