Toyota Repair: 1996 camry misfire, vacuum leaks, coolant temp

Question
QUESTION: Hi Ted,
I have a 1996 camry with the check engine light on.Stored codes are 304,171.I have cleared them a few time and the same one's come back after driving a short time.Most times you can actually here the misfire at idle.Driving under a load esp up a hill it misfires like crazy,although the problem has been intermittent as well.Believe it or not I used to be a Toyota Master tech about 20 years ago.Alot has changed since those days.I have replaced the cap,rotor and wires.Also the fuel filter and the coolant temp sensor (for the efi).All timing marks are dead on.Checked for vacuum leaks and couldn't find anything.The MAP sensor checks ok as well as the air temp sensor,throttle positioner.I applied vacuum to the EGR at idle and the car chugs like its supposed to.I have hit the wall here.I don't know where I should go from here.I have seen very few injector problems with this year and model,but I guess I cant rule anything out.The exhaust system is pretty bad,I'm waiting to fix that after I get it running better.Any help you can provide would be greatly appreciated.Thanks Ted.
respectfully,
William W

ANSWER: Is this a V-6?

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QUESTION: Sorry Ted,..I left out the most important information:1996 Toyota Camry LE 4 Cylinder,auto trans.

Answer
Only a couple of things I can think of, has the compression been tested? If the compression is good then I would start checking for a bad injector, try switching the #4 with #1 and see if the misfire moves to #1, check to make sure the injector wires are not pinched under the valve cover.