white residue in exhaust tips

[cardiffGIANT98gtp]

I was walking around behind my car yesterday and noticed that the inside of the exhaust tips are white.
I did run a bottle of chevron fuel system cleaner through my last tank of gas, probably around 400 miles ago.
I also have noticed a miss developing, but i'm thinking it probably just needs new plugs and wires because i've been doing alot of highway driving lately and haven't done an ignition tune up in about 3 years. Also I think it might be time to do a LIM gasket swap cause i've noticed some coolant puddles on the intake.
Other than that the cars been running pretty good for having almost 150k. Been averaging 29 mpg lately.
But any input would be great, I'm just hoping its not a head gasket getting ready to go.

Thanks everybody.

[FordMan77]

Nope. Probably just residue from the fuel system cleaner. The HG's in these motors are the LAST thing to go, even when overheated they tend to stay put.

I'd lean more towards replacing the LIM gaskets if it's not been done (do you see black between where the LIM meets the head? If so, then change away). Then a basic tune up w/ some good copper or irridium plugs and call it a day. Since the tips are aluminum they can oxidize when a cleaning agent is run through the fuel and hence out the exhaust. Wouldn't worry about it.

[GTPSHAWTY]

i 2nd lim.. my gp ran hot over and over agian due to failed lim but never popped a hg..surprised the chit outta me... it took me 3 hours to get home on a 45 minute trip.. due to running hot and cooling down ...

[cardiffGIANT98gtp]

well thats releaving to hear. i was getting worried that i was gonna have to spend a bunch of money, even though i just bought a new cd player i probably didn't need. lol.