can anyone help my gtb 95 model as a bad misfire at two and a half thousand revs and again at 4 thousand but only under heavy accelleration if i ease the throttle in its ok

My suggestion is to start with normal tune up maitenance. Replace plugs and wires, and see if that helps. Their cheap parts and a cheap fix, if it works. There are other questions in this forum about similar problems; try searching for those and read through them, you'll be surprised about a common problem that sounds similar to yours, but no one has found a fix....yet.

Along with the ignition parts I would also do a compression check to see how things are with the cylinders. There may be an intake manifold leak also.