Car runs great when it isn't warmed up, but after driving it hard and then trying to cruise at ANY miles per hour on ANY gear, the car bogs down. This is how it goes, I keep my foot at the same spot on my gas pedal and cruise at 60 mph. The engine will slow down to 55 then kick back into 60. Slow down again... and kick back to 60mph. This happens on any gear and at any speed.

Can someone tell me whats going on? I have changed the idle air control valve already. The set up is a LS block with b16 head with a chipped gsr ecu. (not sure what kind of chip it is). Aftermarket fuel pump, and thats about it.

It wont stay steady. Let me know what I can do

 

It use to be supercharged
Do you guys think it just needs a good tune?

Let me know thanks!

 

Hmm, so your engine was (hopefully) tuned to expect like 6-8 PSI and now it's seeing nothing by vacuum....hmm, what do you think?

Get that batch tuned.