Toyota Repair: Carina II - 4A-FE - engine problems, air flow meter, air intake system

Question
Hello Ted,

It's now 8 days of trying to finding the problem at my Carina II 4A-FE , year 1990.
Engine works fine in idle, when given throtlle it don't want rev and makes "back fires" into air intake system.

Since now, I have been checkin out allmost everything what was possibile.

- timing belt is o.k. (number 2 on photo)
- injectors are cleaned, tested and o.k. (no.1)
- fuel pump is o.k - pressure is normal (no. 6)
- fuel filter is new (no.7)
- distributor, cabels and spark plugs new
- throttle position sensore - o.k. (no. 5)

What I have done today is (my luck that I have found it on one old Carina):

- replaced Manifold Pressure Sensor or vacume sensore
(number 3 on photo bellow)
- replaced also sensore (number 4)

With all dose actions, problem stays the same.

I'm starting to think that the problem may cause a broken
wire somewhere cause the problem has accured in one moment
(never before I had a single problem in engine work) and the only possibility is a broken wire. Also when I unplug MPS and try give throttle engine work is a little bit beter but still not normal, I have changed that
MPS (Manifold Pressure Sensor (no.3)) but no changes.

p.s. this engine has no air flow meter sensor, it's written in toyota manual I think insted of that is Manifold Pressure Sensor wich I have changed
but without results.

Ted, you are my last hope !

p.s. photos of my engine is at www.karasi.hr/toyota


Answer
The only other thing that I can think of that may be the cause of this problem is the coil inside the distributor, remove the distributor cap, the rotor and then the plastic cover on the coil then check for cracks on the coil surface or burned areas on the coil body, check on the underside of the coil for any burned spots where the current may be jumping to ground.