1986 Toyota Celica GTS

1986 Toyota Celica GTS. 2.0, has the 3S-GE motor.

It's a stick, has 86k miles ( yes that's accurate )
the car sat for several years in a garage and a teenager had it before me for about a year,
so there are some silly things done to it but all in all a great buy when I found it this year feb.

The car had power, very quick and peppy. A joy to drive.
2 months ago the car lost it's power / acceleration.
Not to mention the MPG has significantly decreased.

Replaced:
Plugs, catalytic converter and fuel filter.
Wires were replaced last year in December. ( They looked new when I bought it)
Also the K&N air filter I took off and cleaned thoroughly and properly.

Best way I can describe the problem. It's as if I can only give the car 1/4 throttle. Floored, or barely pushing the pedal, same rev speed.
super slow to rev up to 3.5k rpms. Then it gains some power back.
literally no power while driving in ANY gear unless it's over 4k rpms.
If i'm driving in 5th on the highway, any incline causes the car to loose speed. ( Even at 80 mph )

when I got this car, it would hit 100 on the hwy quickly, no issues

I'm thinking:
A, compression is gone in one or more cylinders. ( New rings? )
B, Fuel pump weak ( altho I figure this would affect power at higher rpms?)
C, a sensor.



I'm not a mechanic, but pretty handy with tools and I can read a manual well.

Any thoughts or input would be greatly appreciated as I NEED THIS CAR DAILY.