1995 3.8 Part Throttle Miss-Sometimes

My 1995 3.8 has developed a part-throttle miss. Doesn't happen all the time, and never at idle or heavy throttle. At first I thought I had received some water in my gas, but it's been too long now.

I'm suspecting the throttle position sensor or the airflow meter. Any way to check them other than buying new ones? Any other ideas?

TPS will throw a code 21 or 22.... www.avigex.ca/xport/dtc21.jpg and following that, 4th and TCC will not engage. THis one is a simple potentiometer...variable resistor and it can be checked for continuity with an ohmmeter: www.avigex.ca/xport/tpsloc.jpg A and C will show a few thousands ohms...and reading between A and B or B and C must give a continuously increasing (decreasing) value with no misses or jumps.
I have solved MAF problem in the past by removing the MAF (three screws) and carefully cleaning the tiny wires with an artist paintbrush and alcohol.
http://www.avigex.ca/xport/maf4864s.jpg

Thanks, LMP

Saturday I gave up and took the van to a dealership. Still waiting for their reply. I have the service manuals for the van and it "appeared" to say I had to use a scanner to read the codes--instead of the old way of reading blinking lights.