Need some advise for 86 GLH turbo
 

I am currently have a wierd acceleration problem that noone can figure out. Under normal driving condition my GLH skips everytime it hits 2800-3200 RPM. When accelerating hard, it does not do this. Also when cruising on the expressways, it constatly does it, so I either have to drive 55 or 85. Replaced computer, power module, alternator, battery, distibutor and cap, coil, spark wire, plugs, MSD box. Had all grounds looked at, just can't put my finger on it. Any help would be greatly appreciated.

Also is it a major deal to replace the Head gasket, and isn't it a thicker gasket. The old one blew last weekend.

Thanks