Another day another problem

I had a similar problem only it started a round 4000, turned out to be spark plug gap. Its seems simple but had me stumped for a little while .
Good luck.

have you checked to make sure plug wiring order is right.? some twit wired mine like a regular 302 and i was experiencing kinda the same thing.

mine did the same thing when I replaced my headgaskets. Turned out I had the distributor one tooth off.

ditto on checking the firing order. roller and non-roller 302's have a different firing order I believe

Just re-read your post. You might consider your mas air meter. My car ran great with a C&L 73mm when I had the stock heads and cam, but when I switched to my current combo in my sig, it wouldn't idle, it would lean-pop at times, stall, surge, etc... I switched to a Pro-M 80mm and it has driven nearly perfect ever since

Do the obvious...

Dump the codes and see what the computer says is wrong…

Here's the link to dump the computer codes with only a jumper wire or paper clip and the check engine light, or test light or voltmeter. I’ve used it for years, and it works great.

See http://www.troublecodes.net/Ford/
OR
See http://www.mustangworks.com/articles/electronics/eec-iv_codes.html

IF your car is an 86-88 stang, you'll have to use the test lamp or voltmeter method. There is no functional check engine light on the 86-88's except possibly the Cali Mass Air cars.

Codes have different answers if the engine is running from the answers that it has when the engine isn't running. It helps a lot to know if you had the engine running when you ran the test.

Trouble codes are either 2 digit or 3 digit, there are no cars that use both 2 digit codes and 3 digit codes.

For those who are intimidated by all the wires & connections, see http://www.actron.com/product_detail.php?pid=16153 for what a typical hand scanner looks like. Normal retail price is about $30 or so at AutoZone or Walmart.

Or for a nicer scanner see http://www.midwayautosupply.com/detailedproductdescription.asp?3829 – It has a 3 digit LCD display so that you don’t have to count flashes or beeps.. Cost is $35.