Won't pass emissions, high hydrocarbons

[Jacfourteen]

first off this isn't for a cavalier, it's for a 94 ford ranger with a 2.3 4 cyl. (My cavi has a bigger motor, lol), but since emissions is a general topic anyway I think it is still relavant (and you cavi guys are better than the ford ranger guys anyday!). Anyways, I took my ranger that I sold to my brother-in-law in to get smogged last week (Ca emissions) and they said it was putting out 280 ppm hydrocarbons (H/C) at idle (max is 120), so the guy said do a tune-up and add some injector cleaner in the tank then bring it back. so I added a little seafoam to the oil ran it for about ten minutes, changed the oil, ran some seafoam into a vac line, added some lucas injector cleaner into the tank, and changed a egr sensor (there was a code for this in the ecu), the plugs and air filter have been changed recently so I didn't do them. Since then it's been ran about 100 miles and I took it back in today. So the guy hooks it up and guess what?, now its reading over 400 ppm H/C! So my question is, what causes high H/C? I know that it is unburned fuel, but what parts of the engine or emissions equipment would account for this? The guy at the smog shop said to change the plugs and wires, change the air filter, and check for a partially open EGR. These sound good to me, but what else should I do? I was thinking of cleaning the maf sensor (do cavi guys know what these are? lol), iac valve, and tb plate. also, just as a note the cat. conv. was changed about 18 months ago, and all cylinders had good compression last time I checked, but I'm gonna comp test again when I change plugs. Anyway any help is appreciated, thanks in advance.