My 93 Camry 5S-FE (about 110K miles) is running rough, hesitating and seems to be misfiring. At idle the RPMs are normal but rough and when moving and on the gas it’s very rough with a lot of vibration and loss of power. When started cold it will idle correctly for a 2 or 3 seconds once every 20 seconds – it’s as if something is kicking in/out. Rapping on the EGR valve does not change anything.

Recent work:
IAC valve removed/cleaned, new IAC & TB gaskets (Nov ‘08)
Timing belt, water pump, oil seals (Oct ’08)
Plugs, wires, cap, and rotor replaced (Jan ’07 – but just 15K miles ago)

Advice appreciated.

Try a vacuum test on the intake manifold to see if there are any vacuum leaks. Vacuum should be 19-21 inches
Take a look at the condition of your vacuum hoses.

How does it run once it is warmed up ?

How does it run once it is warmed up ?

All the roughness, hesitation, vibration, loss of power, symptoms continue once it's warmed up. Only difference between cold and warmed up is that the intermittent moments of normal idle are gone once warmed up.

Should have put this in first post... Check Engine light is not on.

If you can get a vacuum test done on it this will also tell you if your catalytic converter is plugged up.

The typical candidates are:

1) Worn/oxidized cap & rotor contacts
2) Spark plug gaps have eroded (~0.001" per 10,000 miles by my measure)
3) Plugged/sticking EGR valve
4) Plugged/sticking PCV valve
5) Plugged/sticking IAC valve

A good dose of engine cleaner like Seafoam can help clear out deposits as well, but check the above first.

If you can get a vacuum test done on it this will also tell you if your catalytic converter is plugged up.
More recent maintenance (I should have mentioned in my first post):
-Exhaust was replaced in October also including the down pipe, cat, resonator pipe, and muffler
-Distributor cap and rotor replaced 2 years ago
-Seafoam'd 2 years ago

Tonight I inspected the plugs. Cylinders 1, 2, 4 looked fine. #3 was fouled with oil. I'm going to replace the plugs and wires tomorrow since it's cheap and the current wires are Bosch which I now understand are not as good in a Camry as NGK. Also inspected inside the cap - looks fine just a little crust on the terminal posts.

More on the symptom... It smooths out once the revs are over about 2500. It's the worst when the engine is warm and at idle or attempting to rev up from idle past 2500. A lot of sputtering out the tail pipe.

The fouling will cause a misfire, poor idle and acceleration. Plus, caps & rotors will form enough oxidation to affect the spark after just 20,000 miles...I replaced mine and it was running rougher after that short a mileage. I could even see a bright, shiny line along the rotor's edge where the cap posts' oxidation had formed thick enough to actually touch the rotor and scrape it clean.

The oil leak into #3 should be investigated further with a compression test. Check all the cylinders. If any are low relative to the others or below spec, squirt some engine oil into the spark plug hole and retest. Improvement means the piston rings are worn. No improvement means it's the valve seals. Good luck!

OK. This morning I measured the resistance on the ignition coil and found it to be out of spec. Tonight I replaced the coil (Toyota OEM), spark plugs (NGK), plug wires (Toyota OEM), and PCV valve and now its running well again. Maybe even with a bit more power than before.