Toyota Repair: Camry misfire / splutter at low revs, head gasket leak, fuel starvation

Question
Hi,
I have a 1998 4 cil Camry which had a head gasket leak onto cil 4 at about 137000km.  I lifted the head then and had the head refurbished - the problem was due to corrosion forming between a water jacket and cil 4.  I doctored the top of the block corrosion before fitting the refurbed head so I am sure that is fine.  Temperature is normal and no water dissappearing.  It ran fine for 10000km after that job.  Then, on cold starts, and the odd hot start, it would run very roughly, then smooth out after ten seconds and would run perfectly.  At about the same time my Ford Ute started to show signs of fuel starvation on hills and developed a bad "flat spot" on low revs.  I thought that the E10 fuel I have been using the last few months from the same garage (both cars always refuelled there) was the issue - the garage misteriously went for a major refurb, so I wondered about the fuel supply.  I replaced the Fords' inline fuel filter (which was filthy) and added injector cleaner, and it fixed itself after two tanks of fuel.  However, the Camry changed its tricks with no attention to it - it now starts smoothly but developed a low rev low speed splutter.  I tried the same fix as with the Ford, but 1000km on, no change.  Below 2000 revs its pretty bad, runs on 2 or 3 cils, then picks up suddenly and revs perfectly and runs well at speed.  It idles perfectly, no misfire.  On idle with a sudden opening of the throttle, it stumbles and splutters, but as soon as it gets revs, its fine.  I noticed the air intake to be slightly loose as if it may suck in air right where the air filter pipe connects to the manifold, tightened that, no change. I am normally meticulous with gaskets, so I am sure there's no manifold to head intake leak - all vacuum and electrical connections are clean and tidy.  I don't think a strip down of injectors and clean would help as it runs so smoothly over 2000 revs.  I simply have little time to fiddle at the moment and hoped you can help with a quick checklist?  There's no engine light after start, so I don't think the engine management systems sees the problem.  I don't have a scanner, will that tell me anything - is it worth purchasing?

Thanks,
Regards
JD

Answer
Hello, a code reader/scanner is a good investment if you like to do a lot of your own repairs and you sound like you are knowledgeable. This year camry does use the OBD II system but does not monitor engine misfires but it does monitor input signals from the all of the sensors and if there is a fault the check engine light should stay on but you say this is not the case.
It sounds like there is an electrical issue in the secondary ignition system, have you tried spark plugs, distributor cap and the rotor? Also on this engine the ignition coil is inside the distributor, I think this year still had one, correct me if I'm wrong but if it does check the coil carefully as these have a tendency to crack along the top and also develop high voltage leaks to ground which can be temperature related and intermittent.