Interminttant off throttle returning to idle, engine will not respond
Ls3 bottom end, AFR heads, cam, fast intake, in an off road car. Th400, no vss. Tuned several month back and customer said it would fall on its face sometimes. Never had an issue the 2 times I had it on the dyno then. Test drove it last week on the street and could get a weird spot where it would just not respond to throttle input. He had changed several things, fuel system, and air intake, along with new MAF as the old one looked like it might be going bad. Got it on the dyno, spent some time messing with the idle. It was fine before but something had changed. Found a screw missing from the TPS and it was cracked. Replaced and relearned. Also adjusted the screw on the TB and relearning. Now it idles great, makes great power on the dyno and never gave me a hiccup. Pull it off the dyno and take it down the street to see how it reacts in the real world. Again was doing great till...We get on the throttle and then off to come to a stop. It came to a idle but you couldnt get it to come out of it with the throttle. In the attached picture is the spot that it was happening. You can see TPS getting signal, but it wouldnt rev up. The only things I noticed was the o2s reading lean for some time, once they started switching it came back. Also noticed that MAP was high for not being out of idle. At idle it was normally around 50, while in the bad spot it was 70-85. All of this was in gear.
Thoughts? Things I need to check? Tune wrong somewhere?
This happened the one time last week when the customer brought the car down and again after tuning. Wouldnt do it on the dyno after tuning. Only real world. Took it for a second test drive and it didnt do it.
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