Toyota Repair: Code P0300 and P0303, camry v6, head gaskets

Question
Ted,I've been having problems with my 1999 Camry (V6, 54,000 miles) ever since I had the V6 head gaskets replaced at the Dealer.  The day after having the work done the check engine light went on.  After reviewing your answers to others questions I went to Autozone and rented their equipment.  It read EGR insufficient.  The Autozone employee was kind enough to show me where the parts were and he noticed that the EGR hose wasn't connected so he connected it and I erased the code.  That solved that problem.  Then a month later, today, while driving up a hill on the freeway the check engine light went on again but was flickering.  It ended up going off until around 20 miles later when it flickered again (the car wasn't running good when it flickered).  Then when I got off the freeway it flickered around 4 times then instead of flickering it stayed on.  We went to Autozone and checked out the code.  This time it says P0300 and P0303.  Can you help give us advice as to what we should do ?  I am so glad there is this website and that you volunteer for it.  It really has helped us and it helped alot to learn about Autozone (they are terrific.  Very helpful employees.).  Thank You!

Answer
The 300 code is a random multiple misfire, the 303 code is specific to the number 3 cylinder, it has a misfire, it is common for the coil packs to develop problems, there are three coil packs on the front valve cover, each one fires two spark plugs, locate the coil pack that also fires the number 3 cylinder, look at the plug wires there are marked, find the one that goes to the number 3 cylinder and replace that coil pack.