91 Toyota Surge problem?

[91 yota man]

I have a 91 Toyota 2 wheel drive pick up and have been having a problem with it surging as I am driving. I first noticed it on the freeway as I maintained constant speed. It would only surge for a second or two and then go away. This is very sporadic and does not happen at any certain time or speed. If I accelerate the problem would stop. I changed the fuel filter, thinking it may have been partially blocked; but no improvement. As part of regular maintenance I recently changed the spark plugs and this only seemed for make the problem worse. Now when the truck is cool it runs as it did before, but when it warms up it is hard to accelerate. Now when I am at idle the engine is running very rough. I am at a loss and trying to figure out what the problem is. If anyone can help me, it would be greatly appreciated.

[eponator]

but when it warms up it is hard to accelerate

Leads me to believe when the engine warms up something is expanding and causing a leak. I would spray down the vacuum hoses along with any intake gaskets first with carburetor cleaner while the truck is idling and see if that causes the engine to rev up. If it does, you have a vacuum leak.

Otherwise, I would look into the MAF sensor. You might have an air fuel regulation problem at idle as you mention it behaves normally under accelerattion when on the freeway. That would be my best guess. Hope it helps!

[91 yota man]

Thanks, I will give it a try.

[eponator]

Hey Yota man! just curiouse if you managed to fix er up yet and what the problem was?