Toyota Repair: Engine runs rough occasionally, camry xle, infrequent intervals

Question
Car is a 1994 four cylinder Camry XLE.  Problem started when engine was running but car was in either neutral, park or drive, and with or without A/C on.  At infrequent intervals it would hesitate until it was in drive, then it would run perfectly, even after stopping.  This started happening more frequently. Also, it began acting rough when starting to move forward until it reached a higher speed.  Now I am having difficulty getting it to reach a higher speed.  I am using fuel injection cleaner in the gas, replaced spark plugs and ignition wiring and checked the vacuum lines for splits.  

Answer
It could be a fuel quality issue. It could be an egr valve not fully seated. I would need to see the Data list for the engine when its malfunctioning. Wouldnt be a bad idea to check for "pending" codes in the ECM.
Have you had any repaires donr to it?
What is the mileage?

Mike