Ok my GTP has about 67K on it. Has clean oil, less than 100 miles ago the injectors were cleaned with Sea Foam, and had spark plugs changes (AC Delco).

When the vehicle is in park or neutral (i like to put into neutral sometimes so I dont have to hold the brake. Im used to stick) it will rock a little bit. The RPM Gauge doesnt bounce our anything out of the ordinary. There are no odd sounds coming eather. Just a light rumble in the seat and floor. It will happen about every 7 seconds. It is definitely noticeable by me and a passenger.

I am a little concerned on why this is doing this. Any suggestions?

Thank you!

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How To: E-Brake Pwn
2001 GTP. D/S Rotors * Custom Intake * DHP PCM *

Every 3800 I've ever sat in does that. Normal operation.

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2004 Impala LS - got some mods
NAIOA Moderator

Making you think twice before picking on Impalas

My car shakes some too, but it's probably the cam.

When did you start noticing the shake, or has it always been there?

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04 Indy SS build #972
XP, TOG's, Lightning injectors, 2.8 pulley, 105 CC springs, Wizaired, 3.29 gears, tripleedgeperformance ported blower, machined LIM, 180* tstat, RS12YC@.053, FP rewire, Alt rewire, stage 1 V boost, PRJ wires, Stage 2 IC

i noticed it on mine too.

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Wizaired cai,taylor 8mm wires,ngk tr55 plugs, msd coils.slp power flo exhaust w/gtx tips. future mods:zzp 1.0 pcm,slp headers, zzp hv3 uim runners ,zzp hv tb,gmpp sway bars,kyb agx struts,18"A.R.M:Rogues wrapped in firestone firehawk gt's.that's all performance wise.

With the miles, I'd check the condition of the motor mounts and braces. Mine had a slight shake to it and when I pulled the motor, found I had a busted motor mount. Now I don't seem to have the shake anymore. Just something to think about.

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97 GTP~K&N Cold Air Intake~3.4" S/C Pulley~Cat Back Exhaust~MSD Blaster Coil Packs~MSD 8.5mm Wires~NGK TR55IX Plugs~More To Come

It kind of sounds like the random misfire that every single car I've owned has had before. But then again, it's difficult to say how it feels to you vs. how it feels to me.

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GreenBastardPerformance2000 GTP Coupe (the green bastard)
XP, Pacesetters, LS1 TB & MAF,MSD System, P&P LIM, P&P GenV w/ 3.2, 3.0, 2.8, Devil'sOwn Injected 100% Methanol,PowerTuned, TripleEdge Trans w/3.29's
12.92 @ 105mph

Yea, its not really a alarming feeling. Just a few small jolts about ever 7 - 10 seconds. My brother's 04 GTO does it way worse! His has 23K on it and the damn thing rumbles at a dead stop sometimes. I make fun of him about.

And my GTP's air is colder than his GTO

BUT!! GTO.... That car is crazy fast! it will do 120mph NO PROBLEM in 6th sitting at about 3.5K rpm. Its fun Bad gas though >:| Premium too!

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How To: E-Brake Pwn
2001 GTP. D/S Rotors * Custom Intake * DHP PCM *

im gonna say its either a misfire, or a bad motor mount.

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zzp1.0, k&n cai, c.c. plog, 1.9 RR's , 105#'s, 3in o/r dp, res delete, 104's, 8.5mm wires, 180* thermo, 3.4, AEM wideband, TOGs and borla catback on the garage floor.

wit my experience with cars. i'd check, already stated, the motor mounts.

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I agree on the misfire. Mine is doing it right now and I'm getting misfires on cyl #3. Do you have the SES light on? Is it flashing too by chance? It can be a pending code too, if it's not lit up. If you have an OBD II tool check the codes and if not, stop at an Autozone and they can check for free.