My 1986 Firebird 2.8L V6 loses power while driving. I replaced the plugs, wires, cap, Mass

[Steve S]

My 1986 Firebird 2.8L V6 loses power while driving. I replaced the plugs, wires, cap, Mass

air,? I also cut off the exhaust, checked the Cat, checked the transmission. I was able to get the car to a top speed of about 70 on the interstate but going up hills it would slow to about 30. I also replaced all of the vacuum lines and did regain some of the power back. I can drive it around the block and it seems like I have the normal power there. After that, the headlights dim a little and then come back full brightness but I start to lose the acceleration. In Park, I can step on the gas and the motor revs with no hesitation and seems normal. Any ideas on this problem???

 

[j j]

After the car has warmed up open up and take off the oil cap. If you see smoke coming out then it is an internal gasket leak. Get rid of it as soon as possible. Stick your finger in the exhaust pipe, if there is oil or antifreeze on fingers then not good. indication on internal gasket leak.
take transmission dipstick out (if auto) if has bubbles not good and if fluid looks burnt red not good. then time to sell. Sounds like a gasket leak sucking air but it could be numerous stuff as well.

 

[Micah]

....time to sell

 

[Youngmug]

is it an automatic or manual?

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[DOC]

Could be timing or lack of fuel pressure, but it is also possible
it may be the alternator going out. Do a simple test, start the car, losen the positive cable on the battery, and pull the terminal off of the post, if it dies the alternator is going out. It gets in a situation where its needing to pull a heavy current and can't do it. Thats my suspicion but I could be wrong.

 

[tooldaddy2003]

Check for a clogged fuel filter...it may surprise you !!!! The dimming of the lights might be the voltage regulator kicking in.....

 

[Goatman]

air,? I also cut off the exhaust, checked the Cat, checked the transmission. I was able to get the car to a top speed of about 70 on the interstate but going up hills it would slow to about 30. I also replaced all of the vacuum lines and did regain some of the power back. I can drive it around the block and it seems like I have the normal power there. After that, the headlights dim a little and then come back full brightness but I start to lose the acceleration. In Park, I can step on the gas and the motor revs with no hesitation and seems normal. Any ideas on this problem???

Depending on the mileage you may have ring or camshaft wear causing the lack of power, also a stretched timing chain can cause simmilar power loss on the highway.. have you noticed any smoke or unusual exhaust ?
possibly black smoke ?
the fuel injection system could be running rich because of a malfunctioning sensor (coolant temp sensor comes to mind) that will cause lack of power and black smoke ..
the suggestion about the alternater possibly going bad is also possibly something to check on but DO not do the wire off the battery trick it could damage the electrical system instead take the car to your local parts store and have them check the alternater output with the proper tools (most places will not charge for the service) and you don't risk damage ..
Good luck ..