90-305 Formula, just had valve job. I've got the timing set right at 6 degrees, and set the valve lash at a quarter turn. After figuring out that it was running like crap becuase the gas was 18 months old, I've got it running pretty good now in the garage at idle. When I drive under load (accelerating) it feels like a cylinder is missing and I'm definitely not at 100% power. Good spark on all plugs. Could it be that I need to take the lash down another quarter turn? Any thoughts?

Lancer

Do you have the spark plug wires on correctly, you might have a few switched.

More likely you have one of the valves set too tight.
Find the missing cylinder and loosen off the valves on that cylinder. Then readjust them.
A compression test or simple cylinder balance test (temperairily disable the spark on one cylinder at a time)will find the offending cylinder. If thats the problem finding the dead cylinder will be easy.

Dang! talk about missing the easy stuff. OK, so I had 7 and 6 switched in the firing order - and I swear I double checked it the first time, guess I must have been dreaming about how sweet it was going to drive when it was done as It's been in the garage for almost two years now. So, now its running a bit smoother, but I have a slight stutter when I hit the gas. I can hear the air jump in the plenum (I ported it out a bit when disassembled), then a split second gasp before accelerating. What do you think, should I take another pass on the valve lash?

I'm about ready to take a high speed pass through the neighborhood but I think I'll wait till tomorrow until I get insurance back on the car.