stumble at idle

[shawndzugas]

My '90 Suburban(350 TBI) "stumbles" occasionally at idle. Not really a miss, does not come close to stalling. It just loses its rhythm from time to time. It has 41,000 miles on it. I have replaced the O2 sensor, PCV, Air filter, plugs, fuel filter and cleaned the injectors. The cap and rotor look good with no arcing. The plug wires are good also. Am I missing something or should I just replaced the cap, rotor and wires since these are the only parts I can think of that I haven't replaced. Thanks

 

[91GMCSuburban]

vacuum leak?

 

[tx_sub]

i have the same problem but my sub's got 185k miles. i think it started happening after i put in the injector spacer. i also put in new injectors and injector pod cause i fouled the threads on the old one. i tried to find a vacuum leak with a piece of fuel line, but no luck. i haven't replaced any other stuff yet. it happens in gear and in park and neutral. so ttt