I have had my '93 ES300 for about a year and a half now. In the last 6 months, the acceleration has been getting worse and worse. Now, I can press the pedal to the floor, and the car will surge its way up to about 3,000rpm, and then take off. I couldn't beat a ford pinto in a quarter mile right now. I poured some seafoam into the tank, and it seemed to help, but not nearly enough. It is still terrible. I also cleaned the MAF, to no avail. Any ideas what could be causing this "surging"?

 

also, today I have cleaned out the throttle body, replaced the distributor cap and rotor button, and toyed with my timing, but nothing seems to help.

 

check for codes, the CEL light does not need to be on for it to store a code.

 

You are not suppose to clean the MAF sensor, on this car. $800 for new one.
If you didn't mess with the MAF. Then I would suspect you are having a fuel delivery issue. When was the last time you changed your fuel filter?

 

It is my understanding that the fuel filter in the 1993 does not get changed. It is supposed to last the life of the vehicle. You might have some sludge in the valves. I had my mechanic add seafoam into the PCV line, Ver-r-r-y s-l-o-w-l-y to really clean the valves. There are many how-to's on seafoam in the forums and on youtube. It might help, and then replace your plugs. One or two might be fouled up.

 

If you do not have any codes, check the fuel filter next. If it has not been replaced for a long time, I would just replace it.

The airflow meter is very basic. I have attached a section of the schematic that shows the pinout. The potentiometer uses a 0 to 5 volt reference so it is easy to check the signal output. The other component located in the meter is the IAT intake air temp sensor. This is a temp sensitive resistor. It should read between 2 ~ 3 Kohms at 70 deg.

The switch should be closed at idle

 

I am going tomorrow to have all the sensors checked. My entire family are mechanics, and my father is rather skilled with cars, but not at a mechanic level. We have done everything with seafoam you could do. Im hoping its a code. I doubt it is the fuel filter.

Today 0-40 in 6.9 seconds.
Thats terrible.

My dad describes it as, "falling in a hole", It shoots to 2000-3000rpms, promptly falls back to 1500-2000, then it takes off like a normal car. Its very hard to described, and very frustrating.

 

Plugs and plug wires have also been replaced. Keep in mind, we just completed a complete tune-up on this car.

 

With the key on, engine off, backprobe the throttle position sensor. Slowly open the throttle and watch for any spots where the voltage drops. Do this several times to verify there are no drop outs. If that looks good, I would then check the MAF , again backprobing while slowly pushing the plate inside the MAF open. It sounds like one of these two potentiometers are starting to get worn spots on them, which allows the voltage to drop out.
The symptoms do not really sound like a fuel problem, but if it is the original filter, I would at least check it.
One other thing you could try would be to disconnect the vac line going to the EGR valve, (but I do not believe that this is your problem). Be sure to hook the line back up after testing, it is not a good idea to drive without the egr operational.

 

Thanks for your help. I will try some of this today. I am going to a mechanic today to get all the sensors checked; I think that will help me find my problem. Thanks alot.

 

Well, obviously i had a penhole in my air intake hose, they taped that up and she runs like a......lexus. Thanks for all your help though.