98 Chevy Cavalier that surges

[dcarreno2006]

I have a 98 chevy cavalier that surges when I stay at a steady speed it does it for a fraction of a second then back to normal. The car runs great other wise. It has 150,000 miles on it. I just replaced the spark plugs and wires. There is'nt a check engine light or anything. I can't seem to figure it out.

[dcarreno2006]

still having problems

[randy78]

vacuum leak/intake or hose, bad gasket at intake manifold to head

faulty or ruptured fuel pressure regulator- such as on my brothers 89 celebrity 2.8L MPFI recently that was surging up and down at idle but ran and drove fine otherwise, i bypassed it and then bam it ran perfect no more surging at all, the regulator was ruptured and fuel was coming out of it into the vacuum hose and into the intake and was running it rich and confusing the ECM

also check ignition wires for leaks at the plug boots and at the coil packs

commonly they leak and have spark leak jump to the cylinder head or between coil pack towers

if they are very old or cheap wires then check them for spark leak jumping

rev the engine up a little bit from idle and see if they arc anywhere, it will be pretty obvious and a big spark

you can rev it from under the hood if you stick a finger in the backside of the black palstic voer over the throttle linkage at the TB unit and feel the metal throttle lever, push it towards the front bumper to rev the engine

check the IAC valve, if it has never been removed and cleaned then i would do it, it controls the idle, and they get very carboned up and mess up the idle, clean it and the hole in the intake it sits in out really good with cleaner spray and an air blow gun

make sure the air filter is not dirty

see how it runs without the air filter in it, see if it runs better noticeably