Have a stumble at 1200 rpms....WW

[WW7]

Thought I would ask you guys before going anywhere else..
I have had a (stumble /miss) in my 89 for some time now at 1200 rpms when Im off the gas just cruising along in any gear..It also stumbles if its in park and I take the rpms up to 1200 with no pressure on the motor. I have checked and changed all my ignition parts in the last year including plugs,wires,cap,rotor, ICM,Spark control module and Coil,but still have the stumble. Also fuel pressure is correct at all RPMs..


Here's my question:: Last year when I put my new motor in and put my Hooker headers on, I put my O2 sensor into the bung thats in the number 7 cylinder,this is the way Hookers come from the factory, this means Im only getting a reading from #7 for the ecm to go by.Could getting a 02 reading from #7 only cause my 1200 rpm stumble..Should I move the 02 sensor to the header collector? Will this throw my tune off?? Thanks Wayne

[mike100]

Do you have a bigger than stock throttle body? The tps position to engine vacuum might be off the chart so to speak, and it could be perceived as an unexpected vacuum leak.

also pull the plug off of the fuel pressure regulator to make sure the fuel pressure jumps 3-4 psi when you do. this provides a little instantaneous accel enrichment also.

[C4fan]

I'm not that knowledgable but when I was having a problem with my tps the other day one of the symptoms was a dead spot. But, it was immediate when the peddle was pressed. My tps wasn't working at all.