First of all let me set the stage. My son has a 1990 lumina euro w/ 3.1. it recently blew a head gasket. we replaced both head gaskets, 3 coils, plugs and wires, oil sending unit, motor mounts, O2 sensor, crank sensor, and left axle shaft. Had ignition module tested 3 times at 2 different part stores. All parts had issues of some sort. Since we have done this and put it all back together, at 45-65 mph, this car literally feels like it is going to come apart. We have also noticed bubbles on the transmission dipstick, this is the 4spd auto trans. What do these bubbles mean? I have taken fluid out, the bubbles were still there and the trans whined like it was low on fluid. I have added fluid, bubbles still there, but trans shifts better and a little firmer feeling. We are going to do a trans filter change. Could the trans be the source of the herking and jerking? It is just funny that if you drive around the speed limit in overdrive it herks and jerks (only in torque lockup) with hardly any rpm change. If you speed up to 75-90 mph it is like there are no issues at all. I did not use any kind of sealer on the lower intake gasket, I am worried that it has a vacuum leak at the lower intake. Our issues only become apparrent when car is up to operating temp. When warmed up it still has a little bit of a miss. It does not have a catalytic converter on it. We are about $400 into the car, and I had a shop tell me that they could diagnose it for $140. Really don't want to spend to much more on it, but can't afford not to.

 

Make sure the fluid level is correct. Make sure there isn't a pick-up issue when you change the trans filter. Replace the seal for the filter pick up tube...it should come with the filter.

Any trans lines leaking?

 

fixed bubbles in tranny. i believe it was overfilled or the neck of the filter was cracked. engine is miss- firing. checked front 3 plugs, cylinder 4 was wet with gas, the other 2 plugs were fine. going to check back plugs tomorrow. swapped coils and still have a miss-fire. how trustworthy is an autoparts store's ignition module test?