When I start off the engine in the morning, the RPM goes to 1000 RPM then drops off to zero. To solve this, i keep on start my engine and step on the accelerator till I get to 2000 - 3000 RPM before it goes to the normal reading which is 900 RPM. Let it be noted, that I do this solution for 5 to 10 times before it fixes itself.

When I turn on the AC, there are times that it suddenly drops off to ZERO again. What I do is to step off the accelerator real hard ( while in neutral) before turning the AC.

My father and I brought this to a mechanic and we replaced several parts like High Tension Wires , Spark Plugs, PC Valve, Condenser ( sa carburetor ata to) kasi may mga nakitang palyado. After this, the problem was resolved but it came back after a day.

Ngayon, litong lito na rin yung mechanic. Nde na rin nya alam ang gagawin. Let it be known that the carburetor has been overhauled already. Temporary fix namin is to increase the idling. Ngayon, it's set to 1500 RPM at nagiging 1200 RPM when I switch the AC. Ang nakakainis nga eh minsan, bumababa nang 600 RPM pa din at parang gusto pa ring mamatay nang makina.

My ride is a Toyota Corolla '90 XL5

Here are my questions:
Q1. What can be other reasons for this problem?
Q2. I want to try another mechanic na expert sa ganito especially for Toyota Cars. May maire-recommend ba kayo? I live in Taguig so convenient sana kung malapit lang dito like Makati , Pasig and Pasay.

I would really appreciate your inputs guys.