Toyota Repair: 1993 Toyota 4Runner VR engine, spark plug wires, vr engine

Question
The engine misses during acceleration, especially when cold. The last time we went up to a high elevation, 7 to 8 thousand feet, the problem intensified. It has about 20,000 since tuneup. Over the last four years the problem has got progressively worse.
Thank you for your help, in advance.

Answer
A common cause for engine misfires on this model is that the spark plug wires short out against the egr pipe on the right side, it may help to replace the spark plug wires, the spark plugs and the distributor cap,anfd rotor, has any of this been done and if so what else has been done to try to correct this.