Stumble Problems

[lostsoul71]

Need Help any ideas welcome and Thanks ahead of time! Ok I have a 1987 300 zx non turbo, v-6, 5 speed. New oil pump, timing belt, plugs and wires cap button, new head gaskets worked heads intake upper and lower etc. Ok here is the problem it stumbles between 1400 and 2500 near to the point of shutting off. Acts like (A) lack of fuel or and (B) lack of air. Cleaned mass air flow sensor, Checked Belt timing, Checked distributor timing, set at 20 before top dead center, Checked idle set at 700 rpm, Replaced all Vacuum lines, Checked to make sure no vacuum leaks, has 35-45 p.s.i. fuel pressure. Has good exhaust pressure, will idle and rev without stumble but under load as driving stumbles.

[evildky]

spark? I hear stumble and I immediately think of a spark issue. How doe the plugs look? I'd try to replicate the issue and when it begins to act up, shut the car off and pull the plugs. Look for any signs of oil or coolant fowling. I've had improperly made headgaskets from napa before that leaked coolant into the cylinder.

[lostsoul71]

Had the upper and lower Intake put in the Vat when had the heads reworked to remove any carbon. Cleaned the T.B. too. The warmer the car gets the more it stumbles. Once above 30 mph all seems ok. Had the injectors cleaned also. I just rechecked the Belt timing all is good with it. Replaced the FPR also. Checked the compression all with in few psi of the same. Checked the TPS in specs. Now I have not checked the fuel pressure as driving but seems good as I rev the engine parked. Ok the codes I am getting are the idle switch and crank sensor and 0/2 sensor and detonation sensor As for the spark plugs they look dry no signs of coolant or oil on them. Cleaned all the wiring connectors, and checked the coil too, but I get a Yellow to Orange spark so I am wondering if it's the pickup coil or coil that might be breaking down? As for when the problem started was right after the head gaskets was replaced as this was just last week. Before that # 5 was getting coolant and putting pressure in the coolant. Thank you!

[evildky]

Fix the codes. the crank sensor is part fo the distributor and could cause strange spark issues, and knock. A bad knock detector or just disconnected will casue timing to go all wonkey. I suggest you have a good look at the distributor and the knock sensor. Also a good idea to have a look at your iacv.