Engine pulsing

[m5maniac2001]

When the car is accelerating normaly, usually in 2nd or 3rd (automatic) you can hear a pulsing noise from the engine. The MPG guage swings back and forth and the RPM's increase by 250 each swing by the MPG.

It has recently got worse and was hoping I could find out what it was before the car just stops or is undriveable.

Any suggestions would be great.
Thanks

[Interceptor]

When the car is accelerating normaly, usually in 2nd or 3rd (automatic) you can hear a pulsing noise from the engine. The MPG guage swings back and forth and the RPM's increase by 250 each swing by the MPG.

It has recently got worse and was hoping I could find out what it was before the car just stops or is undriveable.
What about the idle? Pulsating while idle usually means your o2 sensor is bad or you have a vacuum leak somewhere.

[m5maniac2001]

It is fine at idling, just when accelerating from a stop or getting up to speed on the Interstate. It is fine while crusing too.

[Interceptor]

It is fine at idling, just when accelerating from a stop or getting up to speed on the Interstate. It is fine while crusing too.
Check your injectors, spark plugs and do the stomp test - maybe error codes (if any) will tell you what's going on.

[liquidtiger720]

I had a similar problem to yours. My car would pulse ~1000 rpm's when accelerating from a stop but settle down at speed. I never did look at the mpg gauge when it happened. So from what it was for me was a vaccum leak. Of all things, it was a small hose from the intake to the ICV. How that messes things up while accelerating. I dont know. I clamped the end of the hose shut with a few of those metal clamps and it seems fine now. I'll have to replace it someday. So after you check what interceptor said to, look for small vaccum leaks.