Ok, first of all I have a 91 Z28 350 ci with 135, 000 miles on it. I recently tuned it up with BOSCH platinum tip plugs, 8.5mm MSD wires, cap and rotor, changed the fuel filter, cleaned my K&N filters and even added a JET performance Stage 2 chip all at the same time. I added the chip because when I installed my SLP intake runners, I installed a 160 thermostat. I read somewhere that if i changed the thermostat to 160 I would need to change the chip so I did.

So heres the problem. I noticed an unusual lack of power from my Z. That is why I did the tune up, it was due for one anyway (2 years since the last tune up). From a dead stop, I slightly press on the gas (normal driving) and sometimes the car vibrates and shakes, rpm's drop to 0 but comes back up. Almost as if the car was gonna die but doesnt. Before, I would tap on the gas pedal and I would be gone, I would get a good throw back into the seat. Now I would have to floor it at least half way to get a slight kick off the start. And on the freeway, the top end totally sucks now. I just dont know what else could be the problem. the prom chip didnt help either. No power and still the same bad gas mileage.

Well guys, any input would be greatly appreciated. Thanks in advance

H

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SS 17x9.5 wheels,
HOTCHKIS 1"drop springs,
HOTCHKIS tower brace,
Bilstein struts and shocks,
K&N filters,
MSD 6A,
MSD 8.5mm Wires,
MSD Cap & Rotor,
Hypertech airfoil,
SLP intake runner (plennum not ported yet, soon)
High flow cats,
SPOHN panhard bar, lower control arms, and subframe connectors,
Baer front track system,
3" Flowmaster Exhaust System,
2100 Stall High Performance Torque Converter,
300 watt sound system,
and soon to come...ZZ4 crate motor...hopefully.

 

get that 160 stat out of there for starters. Your Car isnt a refrigerator.



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60 Ranchero - Project ( Money Hole )
85 Sport Coupe LG4 - Daily Driver 15.26 @ 87.0
Reader's ride -> My Ride

Just another Hot Rod kid, or thats what they all tell me.
Livin' the Stereotype

 

have you had any luck with your problem yet? i am having a similar problem, only when i hit my gas, it seems like the engine is going to explode, and the rpm's never get over 3000. let us know when you get the solution

 

i have a 160 stat with my stock chip. I noticed when I had a Fast chip in there the car ran like crap so i sent it back.

 

Hah!

No, putting in a cooler stat doesnt mean you have to install a custom prom also.. there are plenty of poeple with more mods than you running the stock unit. Take that out, put the old one in, and put whatever you had before for a stat in, then go from there


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• 83 Z28--ttops, 200k miles--very ragged out. sold, thank goodness
• 74 Z28--slightly modded 383, TH400 tranny, not too quick but fun to drive

 

You might want to rty a fuel filter first.

You may also have some injectors that have retired from active service. You can unhook the IAC, then disconnect them one at a time and see if any of them cause less of a drop in the idle RPM than others; if so, then those aren't working properly.

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"So many Mustangs, so little time..."
ICON Motorsports