91 Camry Problems

Hello Everyone. I was wondering if you guys were able to help me with my camry or else I'm going to be forced to take it to the junk yard.
Ok so the car all the sudden started giving me really low mpg a tank full gives me 116 miles. That wasen't the case a couple months back. Also another thing the car started doing is the fans are not turning off. I turn the car on and the fan is on and its on all the time. Then the last problem is the car sometimes is really sluggish to accelerate. But that only happens sometimes.
What i done so far is a full tune up cables, spark plugs, rotor cap, distributor cap, wires. And i have not had any luck..
hopefully you guys can give me some tips.
THank you in advance.

One last question how many catalytic converters does this car have? Some shops tell me it has 2 and some tell me it only has one in the bottom.

What engine and transmission do you have?

I got the 2.0 k 4 cyl
And I am not sure about the transmission where do I checked that? I thanks

Automatic or manual? Also, which fans are you talking about? Engine cooling fans or heater/AC fans inside the passenger compartment?

It's automatic
Yea the ac ones, and the dual ones behind the radiator. But the ac is no turned t on.

Not in any particular order:

Check your ECM to see if there are any diagnostic codes

Check coolant level

Are your plugs wet with fuel?

Check cold-start injector time switch - may not turn off injector

Check to see if your brakes are dragging.

Check for vacuum leaks in your intake system or pcv system.

Check egr valve to see if it is staying open

Check your air filter

Are your ignition components DENSO or NGK brand? Many ignition components are substandard for use in Toyotas.

Check your ignition timing

Check your cylinder compression

Check the following sensors:
Air flow meter
Coolant temperature sensor
Inlet air temperature sensor
Throttle position sensor

Download service manual:
http://dc303.4shared.com/download/M9KuIgnD/1987-1991_Camry_FSM.zip

Alright thank you.
The ignition spark plug wires and cap are Beck arkley and the the spark plugs are ngk.
Thank you for responding i'll get back to you tomorrow about the rest.
Thank you again.

I also want to know how many miles are on the car.

Fan on all the time means there is a fault with the fan temperature control switch. When that circuit is open, the fans stay on until the ignition is turned off. The switch is screwed into the lower part of the radiator near the middle facing the engine bay. Check that the connector wasn't knocked loose or disconnected, then check the wires for fraying or corrosion, and finally trace them back to a ground and check to make sure it is sound with no rust or corrosion.

If the engine is running poorly, pull the plugs and see if they are wet from coolant or fuel or fouled with oil. Fuel means a spark plug isn't firing properly or injector is stuck open. Coolant means a head gasket leak. And oil means leaking valve stem seals. Finally check the coolant for an oily sheen and remove the oil fill cap and look underneath it for a chocolate milk-looking deposit, which is also a sign of oil and coolant mixing. Could be from bad head gasket, cracked block, or from a failing oil cooler in the radiator.

Hope this helps!