hello i just bought 1987 firebird with 87k miles clean body and engine..
i drove the car had feel funny hard to push the pedal but does moving fine... should be soft and go.. why its hard to push till go fast?

why idle act wired during i turn on the heat by low the engine was shaking and idle go up and down up down up down 800 to 400 to 800 to 400 over again till i turn off stop shaking.. little shaking during no heat or anything.. might Air Valve sensors is bad?

help me out pls

 

Jumpy idle **may** be a vacuum leak. Check the vacuum lines for cracks, tears, broken connectors.

As far as gas pedal being " hard " to press, look for binding // kinks, incorrect line up of the throttle cable, something under the pedal itself like bunched up carpet, or a broken // incorrectly mounted pedal bracket.

( edit )
What is the intake system--
TBI, TPI, Carb?

 

But that normal the engine was so rumble. But sound like something knock. No engine check or anything. Its perfect engine condation. Vacuum line might cracks make engine rumble? Should be smooth..
Intake system Is TPI

 

Guys?? Help me out If can keep the car or I take back to seller to get my money back..

 

Never mind. Please closed the thread. I return the car back to pravite seller and money back. Thanks anways..